HYLN / Hyliion Holdings Corp. - Pengajuan SECLaporan Tahunan, Pernyataan Proksi

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 12, 2025 HYLIION HOLDINGS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 12, 2025 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 ☐ TRANSITION REPORT PURSUANT TO S

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIION

HYLIION HOLDINGS REPORTS SECOND-QUARTER 2025 FINANCIAL RESULTS

Exhibit 99.1 HYLIION HOLDINGS REPORTS SECOND-QUARTER 2025 FINANCIAL RESULTS AUSTIN, Texas, August 12, 2025 – Hyliion Holdings Corp. (NYSE American: HYLN) (“Hyliion”), a developer of modular power plant technology, today reported financial results for the second quarter ended June 30, 2025, and provided key updates on the development and commercialization of the KARNO™ generator platform. Key Busin

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form SD.

Exhibit 1.01 Hyliion Holdings Corp. Conflict Minerals Report for the Year Ended December 31, 2024 Introduction Hyliion Holdings Corp. (also referred to as “the Company,” “we,” “our,” and “us”) is a Delaware corporation. This Conflict Minerals Report (“CMR”) for the year ended December 31, 2024, is presented to comply with Rule 13p-1 under the Securities Exchange Act of 1934 (the “Rule”). The Rule

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission File Number) (IRS Employer Identification Number) 1202 BMC Drive, Suite 100 Cedar Park, TX 78613 (Address of principal

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 20, 2025 HYLIION HOLDINGS COR

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 20, 2025 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 ☐ TRANSITION REPORT PURSUANT TO

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIIO

HYLIION HOLDINGS REPORTS FIRST-QUARTER 2025 FINANCIAL RESULTS

Exhibit 99.1 HYLIION HOLDINGS REPORTS FIRST-QUARTER 2025 FINANCIAL RESULTS AUSTIN, Texas, May 13, 2025 – Hyliion Holdings Corp. (NYSE American: HYLN) (“Hyliion”), a developer of modular power plant technology, today reported financial results for the first quarter ended March 31, 2025, and provided key updates on the development and commercialization of the KARNO™ generator platform. Key Business

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 13, 2025 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 25, 2025 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

HYLIION HOLDINGS REPORTS FOURTH-QUARTER AND FULL-YEAR 2024 FINANCIAL RESULTS

Exhibit 99.1 HYLIION HOLDINGS REPORTS FOURTH-QUARTER AND FULL-YEAR 2024 FINANCIAL RESULTS AUSTIN, Texas, February 25, 2025 – Hyliion Holdings Corp. (NYSE American: HYLN) (“Hyliion”), a developer of modular power plant technology, today reported its fourth-quarter and full-year 2024 financial results. Key Business Highlights •Delivered the first Early Adopter Customer Unit in early 2025 •Secured co

Fifth Amendment to Industrial Lease, dated May 28, 2024, by and between GSNTR ATX 1200 BMC Drive Owner LP, GSNTR ATX 1202 BMC Drive Owner LP, and Hyliion Inc.

FIFTH AMENDMENT TO INDUSTRIAL LEASE This FIFTH Amendment to Industrial Lease (the "Amendment") is made and entered into by and among GSNTR ATX 1200 BMC DRIVE OWNER LP, a Delaware limited partnership ("Building 1 Owner"), GSNTR ATX 1202 BMC DRIVE OWNER LP, a Delaware limited partnership ("Building 2 Owner") (Building 1 Owner and Building 2 Owner are collectively referred to herein as "Landlord"), and HYLIION INC.

Hyliion Holdings Corp. Insider Trading Policy

Hyliion Holdings Corp. Insider Trading Policy (Effective November 7, 2023) Introduction During the course of your relationship with Hyliion Holdings Corp. (“Hyliion”), you may receive material information that is not yet publicly available (“material nonpublic information”) about Hyliion or other publicly traded companies that Hyliion has business relationships with. Material nonpublic information

List of Subsidiaries.

Exhibit 21.1 Subsidiaries of the Registrant State of Incorporation Hyliion Inc. Delaware

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 ¨ TRANSITION REPORT PURSUANT TO SECTI

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 or ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38823 HYLIION

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 25 NOTIFICATION OF REMOVAL FROM LISTING AND/OR REGISTRATION UNDER SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 25 NOTIFICATION OF REMOVAL FROM LISTING AND/OR REGISTRATION UNDER SECTION 12(b) OF THE SECURITIES EXCHANGE ACT OF 1934. Commission File Number: 001-38823 Issuer: Hyliion Holdings Corp. Exchange: New York Stock Exchange (Exact name of Issuer as specified in its charter, and name of Exchange where security is listed and/or

HYLIION HOLDINGS REPORTS THIRD-QUARTER 2024 FINANCIAL RESULTS

Exhibit 99.1 HYLIION HOLDINGS REPORTS THIRD-QUARTER 2024 FINANCIAL RESULTS AUSTIN, Texas, November 14, 2024 – Hyliion Holdings Corp. (NYSE American: HYLN) (“Hyliion”), a developer of sustainable electricity-producing technology, today reported its third-quarter 2024 financial results. Key Business Highlights •On track to deliver initial customer units by year-end and reaffirms guidance of low doub

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 ☐ TRANSITION REPORT PURSUANT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HY

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 14, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 83-2538002 (State or other jurisdiction of (I.R.S. Employer incorporation or organization) Identification No.)

Hyliion Holdings Corp. Announces Transfer of Stock Listing to NYSE American

Exhibit 99.1 Hyliion Holdings Corp. Announces Transfer of Stock Listing to NYSE American AUSTIN, Texas – November 5, 2024 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a developer of sustainable electricity-producing technology, today announced that it will transfer its stock exchange listing from the New York Stock Exchange (NYSE) to the NYSE American exchange. The transition is expected to

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 5, 2024 HYLIION HOLDINGS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 5, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Form of Director RSU Award Agreement under the Hyliion Holdings Corp. 2024 Equity Incentive Plan

Hyliion Holdings Corp. Director RSU Award Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the “Company”) has awarded to you (the “Participant”) the number of restricted stock units specified and on the terms set forth below in consideration of your services (the “RSU Award”). Your RSU Award is subject to all of the terms and conditions as set forth herein and in the Company’s 202

Calculation of filing fee tables.

Exhibit 107.1 Calculation of Filing Fee Tables Form S-8 Registration Statement (Form Type) Hyliion Holdings Corp. (Exact Name of Registrant as Specified in its Charter) Table 1 – Newly Registered Securities Security Type Security Class Title Fee Calculation Rule Amount Registered (1) Proposed Maximum Offering Price Per Unit (2) Maximum Aggregate Offering Price (2) Fee Rate Amount of Registration F

HYLIION HOLDINGS REPORTS SECOND-QUARTER 2024 FINANCIAL RESULTS

Exhibit 99.1 HYLIION HOLDINGS REPORTS SECOND-QUARTER 2024 FINANCIAL RESULTS AUSTIN, Texas, August 6, 2024 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a developer of sustainable electricity-producing technology, today reported its second-quarter 2024 financial results. Key Business Highlights •Secured customer commitments for all 2024 early adopter production capacity and for more than 50% o

Form of Performance Based RSU Award Agreement under the Hyliion Holdings Corp. 2024 Equity Incentive Plan

Hyliion Holdings Corp. Performance RSU Award Grant Notice (2020 Equity Incentive Plan) In consideration of your services to Hyliion Holdings Corp. (the “Company”), you (the “Participant”) are hereby awarded a number of performance-based restricted stock units (the “PSUs”) set forth below, subject to the terms, conditions, and restrictions set forth herein, in the Company’s 2020 Equity Incentive Pl

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 6, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 ☐ TRANSITION REPORT PURSUANT TO S

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIION

As filed with the Securities and Exchange Commission on August 6, 2024

As filed with the Securities and Exchange Commission on August 6, 2024 Registration No.

Form of RSU Award Agreement under the Hyliion Holdings Corp. 2024 Equity Incentive Plan

Hyliion Holdings Corp. RSU Award Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the “Company”) has awarded to you (the “Participant”) the number of restricted stock units specified and on the terms set forth below in consideration of your services (the “RSU Award”). Your RSU Award is subject to all of the terms and conditions as set forth herein and in the Company’s 2020 Equity

Hyliion Holdings Corp. 2024 Equity Incentive Plan

HYLIION HOLDINGS CORP. 2024 EQUITY INCENTIVE PLAN ADOPTED BY THE BOARD OF DIRECTORS: APRIL 8, 2024 APPROVED BY THE STOCKHOLDERS: MAY 21, 2024 1.General. (a)Plan Purpose. The Company, by means of the Plan, seeks to secure and retain the services of Employees, Directors and Consultants, to provide incentives for such persons to exert maximum efforts for the success of the Company and any Affiliate a

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form SD.

Exhibit 1.01 Hyliion Holdings Corp. Conflict Minerals Report for the Year Ended December 31, 2023 Introduction Hyliion Holdings Corp. (also referred to as “the Company,” “we,” “our,” and “us”) is a Delaware corporation. This Conflict Minerals Report (“CMR”) for the year ended December 31, 2023, is presented to comply with Rule 13p-1 under the Securities Exchange Act of 1934 (the “Rule”). The Rule

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission File Number) (IRS Employer Identification Number) 1202 BMC Drive, Suite 100 Cedar Park, TX 78613 (Address of principal

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 21, 2024 HYLIION HOLDINGS COR

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 21, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

Hyliion 2020 Equity Incentive Plan, Form of Amendment of PSU Award Agreement.

February 13, 2024 Re: Amendment of PSU Award Agreement Dear [Employee]: 1.In consideration of your continuing role with Hyliion Holdings Corp. (the “Company”) and continued eligibility for the receipt of additional performance-based restricted stock units in the future, the undersigned (“Grantee”) and the Company are entering into this letter agreement (this “Agreement”) pursuant to which the Gran

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 30, 2024 HYLIION HOLDINGS C

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 30, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission F

Hyliion 2020 Equity Incentive Plan, Form of PRSU Award Agreement.

Hyliion Holdings Corp. Performance RSU Award Grant Notice (2020 Equity Incentive Plan) In consideration of your services to Hyliion Holdings Corp. (the “Company”), you (the “Participant”) are hereby awarded a number of performance-based restricted stock units (the “PSUs”) set forth below, subject to the terms, conditions, and restrictions set forth herein, in the Company’s 2020 Equity Incentive Pl

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 ☐ TRANSITION REPORT PURSUANT TO

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIIO

HYLIION HOLDINGS REPORTS FIRST-QUARTER 2024 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. [email protected] (833) 495-4466 [email protected] HYLIION HOLDINGS REPORTS FIRST-QUARTER 2024 FINANCIAL RESULTS AUSTIN, Texas, April 30, 2024 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a developer of sustainable electricity-producing technology, today reported its first-quarter 2024 financial results. Key Business Highlights •Announced that H2 Energy Group

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 4, 2024 HYLIION HOLDINGS CO

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 4, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fi

KARNO GENERATOR SHOWCASE TM Hyliion Proprietary Information HYLIION® 2024 2 This is a working office and R&D facility, and we want everyone to have a safe and fun experience. Please always be aware of your surroundings, use caution, and look for Hyli

KARNO GENERATOR SHOWCASE TM Hyliion Proprietary Information HYLIION® 2024 2 This is a working office and R&D facility, and we want everyone to have a safe and fun experience.

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 4, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fi

Hyliion Regains Compliance with NYSE Continued Listing Standards

Exhibit 99.1 Hyliion Regains Compliance with NYSE Continued Listing Standards AUSTIN, Texas – March 4, 2024 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a developer of sustainable electricity-producing technology, today announced that it received formal notice from the New York Stock Exchange (the "NYSE") on March 1, 2024, confirming that it has successfully regained compliance with continue

Fourth Amendment to Industrial Lease, dated November 14, 2023, by and between GSNTR ATX 1200 BMC DRIVE OWNER LP, GSNTR ATX 1202 BMC DRIVE OWNER LP, and Hyliion Inc.

FOURTH AMENDMENT TO INDUSTRIAL LEASE This Fourth Amendment to Industrial Lease (the “Amendment”) is made and entered into by and among GSNTR ATX 1200 BMC DRIVE OWNER LP, a Delaware limited partnership (“Building 1 Owner”), GSNTR ATX 1202 BMC DRIVE OWNER LP, a Delaware limited partnership (“Building 2 Owner”) (Building 1 Owner and Building 2 Owner are collectively referred to herein as “Landlord”), and HYLIION INC.

HYLIION HOLDINGS REPORTS FOURTH-QUARTER AND FULL-YEAR 2023 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. [email protected] (833) 495-4466 [email protected] HYLIION HOLDINGS REPORTS FOURTH-QUARTER AND FULL-YEAR 2023 FINANCIAL RESULTS AUSTIN, Texas, February 13, 2024 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a developer of sustainable electricity-producing technology, today reported its fourth-quarter and full-year 2023 financial results. Key Business Highlight

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 ¨ TRANSITION REPORT PURSUANT TO SECTI

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 or ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38823 HYLIION

List of Subsidiaries.

Exhibit 21.1 Subsidiaries of the Registrant State of Incorporation Hyliion Inc. Delaware

HYLN / Hyliion Holdings Corp. / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SC 13G/A 1 tv01153-hyliionholdingscorpc.htm SCHEDULE 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 2)* Name of issuer: Hyliion Holdings Corp. Class A Title of Class of Securities: Common Stock CUSIP Number: 449109107 Date of Event Which Requires Filing of this Statement: December 29, 2023 Check the appropriate

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 13, 2024 HYLIION HOLDING

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 13, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

Hyliion Holdings Corp. Amended and Restated Clawback Policy.

Hyliion Holdings Corp. Amended and Restated Clawback Policy (adopted November 7, 2023) Introduction The Board of Directors of the Company (the “Board”) believes that it is in the best interests of the Company and its shareholders to create and maintain a culture that emphasizes integrity and accountability and that reinforces the Company’s pay-for-performance compensation philosophy. The Board has

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 13, 2024 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

Lease Agreement, dated May 10, 2023, by and between MELINK PROPERTIES LLC and Hyliion Inc.

LEASE AGREEMENT THIS LEASE AGREEMENT (this “Lease”) is made as of May 10, 2023 (the “Effective Date”), by and between MELINK PROPERTIES LLC, an Ohio limited liability company (“Landlord”), and HYLIION INC.

Hyliion Holdings Announces $20 Million Stock Repurchase Program

Hyliion Holdings Announces $20 Million Stock Repurchase Program AUSTIN, Texas –December 20th, 2024– Hyliion Holdings Corp.

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 20, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

HYLIION HOLDINGS REPORTS THIRD-QUARTER 2023 FINANCIAL RESULTS Company Announces Plans to Focus on KARNO and Wind Down Powertrain Operations, Preserving Technology for Potential Future Use or Sale

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Kellen Ferris [email protected] (737) 292-8649 HYLIION HOLDINGS REPORTS THIRD-QUARTER 2023 FINANCIAL RESULTS Company Announces Plans to Focus on KARNO and Wind Down Powertrain Operations, Preserving Technology for Potential Future Use or Sale AUSTIN, Texas, November 8, 2023 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliio

Unaudited condensed consolidated financial statements.

We have HYLIION HOLDINGS CORP. UNAUDITED PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET AS OF SEPTEMBER 30, 2023 (Dollar amounts in thousands, except share data) Historical Hyliion Holdings Corp. (a) Pro Forma Adjustments Pro Forma Hyliion Holdings Corp. Assets Current assets Cash and cash equivalents $ 28,600 $ — $ 28,600 Accounts receivable 140 — 140 Inventory 139 (139) (b) — Prepaid expenses an

Press Release of Hyliion Holdings Corp., dated

Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Kellen Ferris [email protected] (737) 292-8649 HYLIION RECEIVES NYSE CONTINUED LISTING STANDARDS NOTICE AUSTIN, Texas, November 8, 2023 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion” or the “Company”), a developer of KARNO generator and electric powertrain technologies, today announced that it has received notice from the New York

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 8, 2023 HYLIION HOLDINGS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 8, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 ☐ TRANSITION REPORT PURSUANT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HY

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 10, 2023 HYLIION HOLDINGS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 10, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

HYLIION HOLDINGS ANNOUNCES STRATEGIC REVIEW OF ALTERNATIVES FOR ELECTRIC POWERTRAIN BUSINESS

Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Kellen Ferris [email protected] (737) 292-8649 HYLIION HOLDINGS ANNOUNCES STRATEGIC REVIEW OF ALTERNATIVES FOR ELECTRIC POWERTRAIN BUSINESS AUSTIN, Texas, October 10, 2023 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a developer of KARNO generator and electric powertrain technologies, today announced that it has engaged strate

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 ☐ TRANSITION REPORT PURSUANT TO S

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIION

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 8, 2023 HYLIION HOLDINGS C

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 8, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission F

HYLIION HOLDINGS REPORTS SECOND-QUARTER 2023 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Kellen Ferris [email protected] (737) 292-8649 HYLIION HOLDINGS REPORTS SECOND-QUARTER 2023 FINANCIAL RESULTS AUSTIN, Texas August 8, 2023 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a leader in electrified solutions for Class 8 semi-trucks, today reported its second-quarter 2023 financial results. Key Business H

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 27, 2023 HYLIION HOLDINGS CO

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 27, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fi

HYLIION’S IN-PERSON INVESTOR DAY TO HIGHLIGHT HYPERTRUCK ERX POWERTRAIN AND KARNO GENERATOR TECHNOLOGY AND FUTURE APPLICATIONS

Exhibit 99.1 HYLIION’S IN-PERSON INVESTOR DAY TO HIGHLIGHT HYPERTRUCK ERX POWERTRAIN AND KARNO GENERATOR TECHNOLOGY AND FUTURE APPLICATIONS ● Starts installation of first production Hypertruck ERX powertrain system ● Unveils KARNO stationary power 200kW representative model ● Expects to generate approximately $10 million in revenue on sales from vehicles outfitted with Hypertruck ERX and Hybrid po

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission File Number) (IRS Employer Identification Number) 1202 BMC Drive, Suite 100 Cedar Park, TX 78613 (Address of principal

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form SD.

Exhibit 1.01 Hyliion Holdings Corp. Conflict Minerals Report for the Year Ended December 31, 2022 Introduction Hyliion Holdings Corp. (also referred to as “the Company,” “we,” “our,” and “us”) is a Delaware corporation. This Conflict Minerals Report (“CMR”) for the year ended December 31, 2022, is presented to comply with Rule 13p-1 under the Securities Exchange Act of 1934 (the “Rule”). The Rule

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 23, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 9, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission File

Hyliion Holdings Corp. Executive Severance Plan (incorporated by reference to Exhibit 10.1 to the Company’s Quarterly Report on Form 10-Q (File No. 001-38823) filed with the SEC on May 9, 2023).

HYLIION HOLDINGS CORP. EXECUTIVE SEVERANCE PLAN (Effective May 4, 2023) INTRODUCTION On May 4, 2023 (the “Effective Date”), the Board of Directors of Hyliion Holdings Corp. (the “Company”) adopted and approved the Hyliion Holding Corp Executive Severance Plan (the “Plan”). The purpose of the Plan is to attract and retain qualified executives for the Company Group (as defined below) by providing pa

Form of Change in Control Agreement (incorporated by reference to Exhibit 10.2 to the Company’s Quarterly Report on Form 10-Q (File No. 001-38823) filed with the SEC on May 9, 2023).

FORM OF CHANGE IN CONTROL AGREEMENT This AGREEMENT (“Agreement”) is dated as of , 2023, by and between HYLIION HOLDINGS CORP.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 ☐ TRANSITION REPORT PURSUANT TO

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIIO

HYLIION HOLDINGS REPORTS FIRST-QUARTER 2023 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Kellen Ferris [email protected] (737) 292-8649 HYLIION HOLDINGS REPORTS FIRST-QUARTER 2023 FINANCIAL RESULTS AUSTIN, Texas – May 9, 2023 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a leader in electrified powertrain solutions for Class 8 semi-trucks, today reported its first-quarter 2023 financial results. Key Bu

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION (RULE 14A-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION (RULE 14A-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commis

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 17, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission F

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 6, 2023 HYLIION HOLDINGS CO

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 6, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fi

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 ¨ TRANSITION REPORT PURSUANT TO SECTI

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 or ¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38823 HYLIION

Hyliion 2020 Equity Incentive Plan, Form of PRSU Award Agreement (incorporated by reference to Exhibit 10.5(c) to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

Hyliion Holdings Corp. Form of Performance RSU Award Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the “Company”) has awarded to you (the “Participant”) the number of performance-based restricted stock units (“PSUs”) specified and on the terms set forth below in consideration of your services (the “PSU Award”). Your PSU Award is subject to all of the terms and conditions as set

HYLIION HOLDINGS REPORTS FOURTH-QUARTER AND FULL-YEAR 2022 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Kellen Ferris [email protected] (737) 292-8649 HYLIION HOLDINGS REPORTS FOURTH-QUARTER AND FULL-YEAR 2022 FINANCIAL RESULTS AUSTIN, Texas – February 28, 2023 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a leader in electrified powertrain solutions for Class 8 semi-trucks, today reported its fourth-quarter and full

Code of Business Conduct and Ethics, dated September 27, 2022 (Incorporated by reference to Exhibit 14.1 of the Company’s Annual Report on Form 10-K (File No.001-38823) filed with the SEC on February 28, 2023).

Hyliion Holdings Corp. Code of Business Conduct and Ethics (Effective September 27, 2022) Introduction Hyliion Holdings Corp. (the “Company,” “Hyliion,” “us,” “we,” “our”) is committed to maintaining the highest standards of business conduct and ethics. This Code of Business Conduct and Ethics (this “Code”) reflects the business practices and principles of behavior that support this commitment. We

List of Subsidiaries.

Exhibit 21.1 Subsidiaries of the Registrant State of Incorporation Hyliion Inc. Delaware

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 28, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 17, 2023 HYLIION HOLDING

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 17, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 13, 2023 HYLIION HOLDING

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 13, 2023 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

HYLN / Hyliion Holdings Corp / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 1)* Name of issuer: Hyliion Holdings Corp. Title of Class of Securities: Common Stock CUSIP Number: 449109107 Date of Event Which Requires Filing of this Statement: December 30, 2022 Check the appropriate box to designate the rule pursuant to which this Schedule is filed

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 21, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 8, 2022 HYLIION HOLDINGS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 8, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Separation Agreement and General Release, dated September 15, 2022, by and between Hyliion Holdings Corp. and Sherri Baker.

SEPARATION AGREEMENT AND GENERAL RELEASE This Separation Agreement and General Release (“Agreement”) is entered into by and between Sherri Baker (“Executive”) and Hyliion Holdings Corp.

Employment Agreement, dated September 12, 2022, by and between Hyliion Holdings Corp. and Jon Panzer

EMPLOYMENT AGREEMENT This Employment Agreement (“Agreement”) is made and entered into by and between Hyliion Holdings Corp.

HYLIION HOLDINGS REPORTS THIRD-QUARTER 2022 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Sharon Merrill Associates, Inc. Nicholas Manganaro [email protected] (617) 542-5300 HYLIION HOLDINGS REPORTS THIRD-QUARTER 2022 FINANCIAL RESULTS AUSTIN, Texas – November 8, 2022 – Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a leader in electrified powertrain solutions for Class 8 semi-trucks, today rep

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 ☐ TRANSITION REPORT PURSUANT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HY

Other Events, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 27, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissi

Hyliion Holdings Closes Acquisition of GE’s Revolutionary Hydrogen and Fuel Agnostic Generator Technology

Exhibit 99.1 Hyliion Holdings Closes Acquisition of GE?s Revolutionary Hydrogen and Fuel Agnostic Generator Technology AUSTIN, Texas ? September 27, 2022 ? Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 semi-trucks, today announced the September 26, 2022 closing of its previously announced deal to acquire a new hydrogen and fuel agnostic c

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): September 12, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissi

HYLIION NAMES JON PANZER AS CHIEF FINANCIAL OFFICER

Exhibit 99.1 HYLIION NAMES JON PANZER AS CHIEF FINANCIAL OFFICER AUSTIN, Texas-(BUSINESS WIRE) - Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 commercial semi-trucks, has announced that Jon Panzer has joined the company as Chief Financial Officer. Panzer brings extensive expertise in leading financial activities for Union Pacific Railroad

Asset Purchase Agreement, dated August 24, 2022, by and between Hyliion Holdings Corp. and General Electric Company, acting solely by and through its GE Aviation business unit (incorporated by reference to Exhibit 2.1 to the Company’s Current Report on Form 8-K (File No. 001-38823) filed with the SEC on August 25, 2022).

Exhibit 2.1 ASSET PURCHASE AGREEMENT dated as of August 24, 2022 between GENERAL ELECTRIC COMPANY, acting solely by and through its GE Additive business unit, as Seller, and HYLIION HOLDINGS CORP., as Buyer TABLE OF CONTENTS Page Article I DEFINITIONS Section 1.01 Certain Defined Terms 1 Article II PURCHASE AND SALE; CLOSING Section 2.01 Purchase and Sale of the Transferred Assets 1 Section 2.02 A

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Unregistered Sales of Equity Securities, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 24, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

HYLIION ACQUIRES REVOLUTIONARY HYDROGEN AND FUEL AGNOSTIC GENERATOR TECHNOLOGY FROM GE

Exhibit 99.1 HYLIION ACQUIRES REVOLUTIONARY HYDROGEN AND FUEL AGNOSTIC GENERATOR TECHNOLOGY FROM GE ? Generator to be integrated into Hyliion?s Hypertruck powertrain platform to offer a next generation fuel agnostic semi-truck solution ? KARNO generator is expected to be 20%+ more efficient than today?s leading generators; achieved by 3D printing of thermal components and innovative fuel to electr

HYLIION HOLDINGS REPORTS SECOND-QUARTER 2022 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Sharon Merrill Associates, Inc. Nicholas Manganaro [email protected] (617) 542-5300 HYLIION HOLDINGS REPORTS SECOND-QUARTER 2022 FINANCIAL RESULTS AUSTIN, Texas ? August 9, 2022 ? Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 semi-trucks, today repo

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 ☐ TRANSITION REPORT PURSUANT TO S

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIION

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 9, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission F

Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form SD.

EX-1.01 2 ea160708ex1-01hyliion.htm CONFLICT MINERALS REPORT AS REQUIRED BY ITEMS 1.01 AND 1.02 OF THIS FORM SD Exhibit 1.01 Hyliion Holdings Corp. Conflict Minerals Report for the Year Ended December 31, 2021 Introduction Hyliion Holdings Corp. (also referred to as “the Company,” “we,” “our,” and “us”) is a Delaware corporation. This Conflict Minerals Report (“CMR”) for the year ended December 31

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter)

SD 1 ea160708-sdhyliionhold.htm SPECIALIZED DISCLOSURE REPORT UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission File Number) (IRS Employer Identification Number) 1202 BM

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 19, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 10, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 9, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission File

HYLIION HOLDINGS REPORTS FIRST-QUARTER 2022 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Sharon Merrill Associates, Inc. Nicholas Manganaro [email protected] (617) 542-5300 HYLIION HOLDINGS REPORTS FIRST-QUARTER 2022 FINANCIAL RESULTS AUSTIN, Texas ?May 9, 2022? Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 semi-trucks, today reported i

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 ☐ TRANSITION REPORT PURSUANT TO

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIIO

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

DEFA14A 1 ea157384-defa14ahyliionhold.htm DEFINITIVE ADDITIONAL MATERIALS UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ C

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

DEF 14A 1 def14a0322hyliionholdings.htm DEFINITIVE PROXY STATEMENT UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confiden

First Amendment to Industrial Lease, dated December 1, 2020, by and between IGX Brushy Creek, LLC and Hyliion Inc. (incorporated by reference to Exhibit 10.12 to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

FIRST AMENDMENT TO INDUSTRIAL LEASE This First Amendment to Industrial Lease (the "Amendment") is made and entered into by and between IGX BRUSHY CREEK, LLC, a Texas limited liability company ("Landlord") and HYLIION INC.

Amended and Restated Employment Agreement, dated February 24, 2022, by and between Hyliion Holdings Corp. and Jose Oxholm.

AMENDED AND RESTATED EMPLOYMENT AGREEMENT This Amended and Restated Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

HYLIION HOLDINGS REPORTS FOURTH QUARTER AND FULL YEAR 2021 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Sharon Merrill Associates, Inc. Nicholas Manganaro [email protected] (617) 542-5300 HYLIION HOLDINGS REPORTS FOURTH QUARTER AND FULL YEAR 2021 FINANCIAL RESULTS AUSTIN, Texas, February 23, 2022 ? Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 semi-tr

Second Amendment to Industrial Lease, dated June 2, 2021, by and between IGX Brushy Creek, LLC and Hyliion Inc. (incorporated by reference to Exhibit 10.13 to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

SECOND AMENDMENT TO INDUSTRIAL LEASE This Second Amendment to Industrial Lease (the ?Amendment?) is made and entered into by and between IGX BRUSHY CREEK, LLC, a Texas limited liability company (?Landlord?) and HYLIION INC.

Amended and Restated Employment Agreement, dated February 24, 2022, by and between Hyliion Holdings Corp. and Sherri Baker.

AMENDED AND RESTATED EMPLOYMENT AGREEMENT This Amended and Restated Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

Employment Agreement, dated February 24, 2022, by and between Hyliion Holdings Corp. and Cheri Lantz (incorporated by reference to Exhibit 10.20 to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

EMPLOYMENT AGREEMENT This Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

List of Subsidiaries.

Exhibit 21.1 Subsidiaries of the Registrant State of Incorporation Hyliion Inc. Delaware

Amended and Restated Employment Agreement, dated February 24, 2022, by and between Hyliion Holdings Corp. and Thomas Healy (incorporated by reference to Exhibit 10.15 to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

AMENDED AND RESTATED EMPLOYMENT AGREEMENT This Amended and Restated Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

Amended and Restated Employment Agreement, dated February 24, 2022, by and between Hyliion Holdings Corp. and Dennis Gallagher (incorporated by reference to Exhibit 10.17 to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

AMENDED AND RESTATED EMPLOYMENT AGREEMENT This Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 ¨ TRANSITION REPORT PURSUANT TO SECTI

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 or ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38823 HYLIION

Amended and Restated Employment Agreement, dated February 24, 2022, by and between Hyliion Holdings Corp. and Patrick Sexton.

AMENDED AND RESTATED EMPLOYMENT AGREEMENT This Amended and Restated Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

Third Amendment to Industrial Lease, dated December 17, 2021, by and between IGX Brushy Creek, LLC and Hyliion Inc. (incorporated by reference to Exhibit 10.14 to the Company’s Annual Report on Form 10-K (File No. 001-38823) filed with the SEC on February 24, 2022).

THIRD AMENDMENT TO INDUSTRIAL LEASE This Third Amendment to Industrial Lease (the "Amendment") is made and entered into by and between IGX BRUSHY CREEK, LLC, a Texas limited liability company ("Landlord") and HYLIION INC.

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 23, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

HYLN / Hyliion Holdings Corp / VANGUARD GROUP INC - SCHEDULE 13G Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 Name of issuer: Hyliion Holdings Corp. Title of Class of Securities: Common Stock CUSIP Number: 449109107 Date of Event Which Requires Filing of this Statement: December 31, 2021 Check the appropriate box to designate the rule pursuant to which this Schedule is filed: ☒ Rule 13d-1(b) ☐ 

HYLN / Hyliion Holdings Corp / FJ Management Inc. - SC 13G/A Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Hyliion Holdings Corp. (Name of Issuer) (Common Stock, $0.0001 par value per share) 449109107 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this

HYLIION ANNOUNCES COMMERCIAL TRUCKING INDUSTRY VETERAN JAY CRAIG TO JOIN BOARD OF DIRECTORS Former Meritor Executive Chairman of the Board and Chief Executive Officer brings extensive product innovation and commercialization experience

Exhibit 99.1 Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 Sharon Merrill Associates, Inc. Nicholas Manganaro [email protected] (617) 542-5300 HYLIION ANNOUNCES COMMERCIAL TRUCKING INDUSTRY VETERAN JAY CRAIG TO JOIN BOARD OF DIRECTORS Former Meritor Executive Chairman of the Board and Chief Executive Officer brings extensive product innovation and commercialization

HYLN / Hyliion Holdings Corp / Grace Victoria K. - SC 13G/A Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No. 2)* Hyliion Holdings Corp. (Name of Issuer) (Common Stock, $0.0001 par value per share) 449109107 (CUSIP Number) December 31, 2021 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 28, 2022 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 83-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Up to 88,642,440 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 1 (To Prospectus Dated January 5, 2022) Up to 88,642,440 Shares of Common Stock This Prospectus Supplement No. 1 supplements and amends the prospectus dated January 5, 2022 (as amended and supplemented to date, the ?Prospectus?) relating to the offer and sale from time to time by the selling security holders nam

Up to 88,642,440 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS Up to 88,642,440 Shares of Common Stock This prospectus relates to the offer and sale from time to time by the selling securityholders named in this prospectus (the ?Selling Securityholders?) of up to 88,642,440 shares of Common Stock. We will not receive any proceeds from the sale of shares of Common Stock by the Selling Secu

As filed with the Securities and Exchange Commission on December 30, 2021

As filed with the Securities and Exchange Commission on December 30, 2021 Registration No.

HYLN / Hyliion Holdings Corp / AXIOMA VENTURES, LLC Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 4)* HYLIION HOLDINGS CORP. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109 107 (CUSIP Number) Howard M. Jenkins Alexander H. Jenkins 601 South Boulevard Tampa, Florida 33606 (813) 760-2229 (Name, Address and T

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 ☐ TRANSITION REPORT PURSUANT

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HY

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 9, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

HYLIION REPORTS THIRD QUARTER 2021 FINANCIAL RESULTS

EX-99.1 2 exhibit99193021.htm EX-99.1 Exhibit 99.1 Hyliion Holdings Corp. Investor Contact Louis Baltimore [email protected] Press Contact Ryann Malone [email protected] (833) 495-4466 HYLIION REPORTS THIRD QUARTER 2021 FINANCIAL RESULTS AUSTIN, Texas (NOVEMBER 9, 2021)—Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a leader in electrified powertrain solutions for Class 8 semi-trucks, today reporte

Up to 91,394,533 Shares of Common Stock

424B3 1 hyln-202109x30x424b3.htm 424B3 Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 7 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 7 supplements and amends the prospectus dated July 15, 2021 (as amended and supplemented to date, the “Prospectus”) relating to the offer and sale from time to time

Employment Agreement, dated August 10, 2021, by and between Hyliion Holdings Corp. and Dennis M. Gallagher.

EMPLOYMENT AGREEMENT This Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp.

Financial Statements and Exhibits, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 13, 2021 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Up to 91,394,533 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 6 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 6 supplements and amends the prospectus dated July 15, 2021 (as amended and supplemented to date, the ?Prospectus?) relating to the offer and sale from time to time by the selling securityholders named in

Amendment to Employment Agreement, dated October 13, 2021, by and between Hyliion Holdings Corp. and Patrick Sexton

Exhibit 10.1 AMENDMENT TO Employment AGREEMENT This AMENDMENT TO EMPLOYMENT AGREEMENT (this ?Amendment?) is made and entered into on October 13, 2021, by and between Hyliion Holdings Corp., a Delaware corporation (the ?Company?), and Patrick Sexton (?Employee?). Capitalized terms used herein without definition have the meanings given to them in the Agreement (as defined below). WHEREAS, the partie

HYLN / Hyliion Holdings Corp / AXIOMA VENTURES, LLC Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 3)* HYLIION HOLDINGS CORP. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109 107 (CUSIP Number) Howard M. Jenkins c/o Axioma Management, LLC 601 South Boulevard Tampa, Florida 33606 (813) 760-2229 (Name, Address

Up to 91,394,533 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 5 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 5 supplements and amends the prospectus dated July 15, 2021 (as amended and supplemented to date, the ?Prospectus?) relating to the offer and sale from time to time by the selling security holders named i

HYLIION ANNOUNCES AUTOMOTIVE INDUSTRY VETERAN MARY GUSTANSKI TO JOIN BOARD OF DIRECTORS Former Senior Vice President and Chief Technology Officer of Delphi Technologies brings deep engineering and electrification technology experience

Exhibit 99.1 HYLIION ANNOUNCES AUTOMOTIVE INDUSTRY VETERAN MARY GUSTANSKI TO JOIN BOARD OF DIRECTORS Former Senior Vice President and Chief Technology Officer of Delphi Technologies brings deep engineering and electrification technology experience AUSTIN, Texas (August 26, 2021) - Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 semi-trucks,

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 24, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 19, 2021 HYLIION HOLDINGS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 19, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Up to 91,394,533 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 4 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 4 supplements and amends the prospectus dated July 15, 2021 (as amended and supplemented to date, the “Prospectus”) relating to the offer and sale from time to time by the selling security holders named i

HYLIION ANNOUNCES FORMER SECRETARY ELAINE CHAO TO JOIN BOARD OF DIRECTORS Former U.S. Secretary of Transportation and Secretary of Labor brings extensive knowledge in transportation innovation and infrastructure

Exhibit 99.1 For Immediate Release Hyliion Holdings Corp. Press Contact Ryann Malone [email protected] (833) 495-4466 Investor Contact Louis Baltimore [email protected] (833) 495-4466 HYLIION ANNOUNCES FORMER SECRETARY ELAINE CHAO TO JOIN BOARD OF DIRECTORS Former U.S. Secretary of Transportation and Secretary of Labor brings extensive knowledge in transportation innovation and infrastructure AUSTIN,

Up to 91,394,533 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 3 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 3 supplements and amends the prospectus dated July 15, 2021 (as amended and supplemented to date, the ?Prospectus?) relating to the offer and sale from time to time by the selling security holders named i

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 10, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Up to 91,394,533 Shares of Common Stock

Table of Contents Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 2 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 2 supplements and amends the prospectus dated July 15, 2021 (the ?Prospectus?) relating to the issuance by us of up to an aggregate of 91,394,533 shares of Common Stock. On August 11, 20

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q/A Amendment No.1 ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 ☐ TRANSITION REP

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q/A Amendment No.1 ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 ☐ TRANSITION REPORT PURSUANT TO S

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIION

HYLIION REPORTS SECOND QUARTER 2021 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Investor Contact Louis Baltimore [email protected] Press Contact Ryann Malone [email protected] (833) 495-4466 HYLIION REPORTS SECOND QUARTER 2021 FINANCIAL RESULTS AUSTIN, Texas (Aug. 10, 2021)?Hyliion Holdings Corp. (NYSE: HYLN) (?Hyliion?), a leader in electrified powertrain solutions for Class 8 semi-trucks, today reported its second quarter 2021 financial resu

Up to 91,394,533 Shares of Common Stock

Table of Contents Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 1 (To Prospectus Dated July 15, 2021) Up to 91,394,533 Shares of Common Stock This Prospectus Supplement No. 1 supplements and amends the prospectus dated July 15, 2021 (the ?Prospectus?) relating to the issuance by us of up to an aggregate of 91,394,533 shares of Common Stock. On August 10, 20

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 10, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Up to 91,394,533 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS Up to 91,394,533 Shares of Common Stock This prospectus relates to the offer and sale from time to time by the selling securityholders named in this prospectus (the “Selling Securityholders”) of up to 91,394,533 shares of Common Stock. We will not receive any proceeds from the sale of shares of Common Stock by the Selling Secu

As filed with the Securities and Exchange Commission on July 8, 2021

As filed with the Securities and Exchange Commission on July 8, 2021 Registration No.

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 8, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

HYLN / Hyliion Holdings Corp / AXIOMA VENTURES, LLC - AMENDMENT NO. 2 TO SCHEDULE 13D Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 2)* HYLIION HOLDINGS CORP. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109 107 (CUSIP Number) Howard M. Jenkins c/o Axioma Management, LLC 601 South Boulevard Tampa, Florida 33606 (813) 760-2229 (Name, Address

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form SD.

Exhibit 1.01 Hyliion Holdings Corp. Conflict Minerals Report for the Year Ended December 31, 2020 Introduction Hyliion Holdings Corp. (also referred to as ?the Company,? ?we,? ?our,? and ?us?) is a Delaware corporation. This Conflict Minerals Report (?CMR?) for the year ended December 31, 2020, is presented to comply with Rule 13p-1 under the Securities Exchange Act of 1934 (the ?Rule?). The Rule

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report HYLIION HOLDINGS CORP. (Exact name of the registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission File Number) (IRS Employer Identification Number) 1202 BMC Drive, Suite 100 Cedar Park, TX 78613 (Address of principal

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1)* HYLIION HOLDINGS CORP. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Sec

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 1)* HYLIION HOLDINGS CORP. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109 107 (CUSIP Number) Howard M. Jenkins c/o Axioma Management, LLC 601 South Boulevard Tampa, Florida 33606 (813) 760-2229 (Name, Address

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 7 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 7 supplements and amends the prospectus dated November 27, 2020 (as amended and supplemented to dat

Employment Agreement, dated January 8, 2021, by and between Hyliion Holdings Corp. and Sherri Baker.

Exhibit 10.18 EMPLOYMENT AGREEMENT This Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp., a Delaware corporation, (the ?Company?), and Sherri Baker (?Employee?), and shall be effective as of the Effective Date, as defined below. This Agreement is intended to terminate and supersede any employment agreement, offer letter or other employment-related a

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) þ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2020 ☐ TRANSITION REPORT PURS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A (Amendment No. 1) ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2020 or ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38823 Hyliion Holdi

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2021 ☐ TRANSITION REPORT PURSUANT TO

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ? QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2021 OR ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIIO

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Table of Contents Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 6 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 6 supplements and amends the prospectus dated November 27, 2020 (the ?Prospectus?

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 5 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 5 supplements and amends the prospectus dated November 27, 2020 (the ?Prospectus?) relating to the

Code of Business Conduct and Ethics.

Exhibit 14.1 HYLIION HOLDINGS CORP. CODE OF BUSINESS CONDUCT AND ETHICS INTRODUCTION Hyliion Holdings Corp. (the ?Company,? ?Hyliion,? ?us,? ?we,? ?our?) is committed to maintaining the highest standards of business conduct and ethics. This Code of Business Conduct and Ethics (this ?Code?) reflects the business practices and principles of behavior that support this commitment. We expect every empl

Description of Securities

Exhibit 4.4 DESCRIPTION OF OUR SECURITIES The following summary of the material terms of our securities is not intended to be a complete summary of the rights and preferences of such securities, and is qualified by reference to our Second Amended and Restated Certificate of Incorporation (the ?Certificate of Incorporation?), our Bylaws and the Warrant-related documents described herein, which are

List of Subsidiaries.

Exhibit 21.1 Subsidiaries of the Registrant State of Incorporation Hyliion Inc. Delaware

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): May 11, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

HYLIION PROVIDES FIRST QUARTER 2021 BUSINESS UPDATES

Exhibit 99.1 Hyliion Holdings Corp. Investor Contact Louis Baltimore [email protected] Press Contact Ryann Malone [email protected] (833) 495-4466 HYLIION PROVIDES FIRST QUARTER 2021 BUSINESS UPDATES AUSTIN, Texas (May 11, 2021)—Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), a leader in electrified powertrain solutions for Class 8 semi-trucks, today reported its first quarter 2021 business updates.

Non-Reliance on Previously Issued Financial Statements or a Related Audit Report or Completed Interim Review, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 10, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission Fil

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 4 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 4 supplements and amends the prospectus dated November 27, 2020 (the “Prospectus”) relating to the

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants Explanatory Note

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 4 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants Explanatory Note The Prospectus Supplement No. 4 filed with the EDGAR filing system on May 11, 2021 immediately preceding this fil

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 3 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 3 supplements and amends the prospectus dated November 27, 2020 (the ?Prospectus?) relating to the

Schedule 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant S Filed by a party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)

- DEFINITIVE ADDITIONAL MATERIALS

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (RULE 14a-101) SCHEDULE 14A INFORMATION Proxy Statement Pursuant To Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ? Filed by a Party other than the Registrant ? Check the appropriate box: ? Preliminary Proxy Statement ? Confidential, for use of the Commission Only (a

Regulation FD Disclosure, Financial Statements and Exhibits

8-K 1 ea139158-8khyliion.htm CURRENT REPORT UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): April 7, 2021 HYLIION HOLDINGS CORP. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other J

HYLIION FORMS HYPERTRUCK INNOVATION COUNCIL TO ADVANCE ELECTRIFICATION SOLUTIONS FOR COMMERCIAL TRANSPORTATION INDUSTRY

Exhibit 99.1 For Immediate Release Hyliion Holdings Corp. Ryann Malone [email protected] (833) 495-4466 HYLIION FORMS HYPERTRUCK INNOVATION COUNCIL TO ADVANCE ELECTRIFICATION SOLUTIONS FOR COMMERCIAL TRANSPORTATION INDUSTRY ? New collaboration includes fleet and technology leaders Agility Logistics, American Natural Gas, Anheuser-Busch, GreenPath Logistics, NFI, Penske Truck Leasing, Ruan Transpor

Hyliion 2020 Equity Incentive Plan, Form of Restricted Stock Award Agreement

Exhibit 10.2 Hyliion Holdings Corp. Form of Restricted Stock Award Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the ?Company?) has awarded to you (the ?Participant?) the number of shares of Common Stock specified and on the terms set forth below in consideration of your services (the ?Restricted Stock Award?). Your Restricted Stock Award is subject to all of the terms and cond

Hyliion 2020 Equity Incentive Plan, Form of PSU Award Agreement

Exhibit 10.1 Hyliion Holdings Corp. Form of Performance RSU Award Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the ?Company?) has awarded to you (the ?Participant?) the number of performance-based restricted stock units (?PSUs?) specified and on the terms set forth below in consideration of your services (the ?PSU Award?). Your PSU Award is subject to all of the terms and cond

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

8-K 1 ea138819-8khyliionholdings.htm CURRENT REPORT united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 26, 2021 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State o

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 2 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 2 supplements and amends the prospectus dated November 27, 2020 (as supplemented to date, the “Pros

UNITED STATES

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Hyliion Holdings Corp. (Name of Issuer) (Common Stock, $0.0001 par value per share) 449109107 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this

Code of Business Conduct and Ethics.

Exhibit 14.1 HYLIION HOLDINGS CORP. CODE OF BUSINESS CONDUCT AND ETHICS INTRODUCTION Hyliion Holdings Corp. (the ?Company,? ?Hyliion,? ?us,? ?we,? ?our?) is committed to maintaining the highest standards of business conduct and ethics. This Code of Business Conduct and Ethics (this ?Code?) reflects the business practices and principles of behavior that support this commitment. We expect every empl

Employment Agreement, dated January 8, 2021, by and between Hyliion Holdings Corp. and Sherri Baker.

Exhibit 10.18 EMPLOYMENT AGREEMENT This Employment Agreement (?Agreement?) is made and entered into by and between Hyliion Holdings Corp., a Delaware corporation, (the ?Company?), and Sherri Baker (?Employee?), and shall be effective as of the Effective Date, as defined below. This Agreement is intended to terminate and supersede any employment agreement, offer letter or other employment-related a

Annual Report - ANNUAL REPORT

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ? ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2020 or ? TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38823 Hyliion Holdings Corp. (Exact nam

Description of Securities.

EXHIBIT 4.4 DESCRIPTION OF OUR SECURITIES The following summary of the material terms of our securities is not intended to be a complete summary of the rights and preferences of such securities, and is qualified by reference to our Second Amended and Restated Certificate of Incorporation (the ?Certificate of Incorporation?), our Bylaws and the Warrant-related documents described herein, which are

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS SUPPLEMENT NO. 1 (To Prospectus Dated November 27, 2020) Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This Prospectus Supplement No. 1 supplements and amends the prospectus dated November 27, 2020 (the ?Prospectus?) relating to the

List of Subsidiaries.

Exhibit 21.1 Subsidiaries of the Registrant State of Incorporation Hyliion Inc. Delaware

Results of Operations and Financial Condition, Financial Statements and Exhibits

8-K 1 ea136295-8khyliionhold.htm CURRENT REPORT united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): February 23, 2021 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or

HYLIION REPORTS FOURTH QUARTER 2020 FINANCIAL RESULTS

Exhibit 99.1 Hyliion Holdings Corp. Investor Inquiries [email protected] Press Inquiries Liz Hilton [email protected] (833) 495-4466 HYLIION REPORTS FOURTH QUARTER 2020 FINANCIAL RESULTS AUSTIN, Texas (Feb. 23, 2021)—Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion”), parent company of Hyliion Inc. and a leader in electrified powertrain solutions for Class 8 commercial vehicles, today reported its fourt

Joint Filing Agreement (filed herewith).

EXHIBIT 99.1 JOINT FILING AGREEMENT February 16, 2021 Pursuant to and in accordance with the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations thereunder, each party hereto hereby agrees to the joint filing, on behalf of each of them, of any filing required by such party under Section 13 or Section 16 of the Exchange Act or any rule or regulation there

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2)* Tortoise Acquisition Corp. (Name of Issuer) Class A Common Stock, $.0001 par value (Title of Class of

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 2)* Tortoise Acquisition Corp. (Name of Issuer) Class A Common Stock, $.0001 par value (Title of Class of Securities) 89154L100 (CUSIP Number) December 31, 2020 (Date of Event which Requires Filing of this Statement) Check the appropriate box to designate

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Hyliion Holdings Corp.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1) * Hyliion Holdings Corp. (Name of Issuer) Common Stock (Title of Class of Securities) (CUSIP Number) Dece

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1) * Hyliion Holdings Corp. (Name of Issuer) Common Stock (Title of Class of Securities) 449109107 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of This Statement) Check the appropriate box to designate the rule pursuant to which this

Hyliion Holdings Corp. (formerly known as Tortoise Acquisition Corp.)

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No. 1)* Hyliion Holdings Corp. (formerly known as Tortoise Acquisition Corp.) (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109107 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of This Statement) Check t

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Hyliion Holdings Corp. (Name of Issuer) Class A Common Stock, par value $0.0001 per share (Title of Clas

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* Hyliion Holdings Corp. (Name of Issuer) Class A Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109 107 (CUSIP Number) December 31, 2020 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to desi

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 15, 2021 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 8, 2021 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction (Commission File Number) (I.R.

EX-99.25

NOTIFICATION OF THE REMOVAL FROM LISTING AND REGISTRATION OF THE STATED SECURITIES The New York Stock Exchange hereby notifies the SEC of its intention to remove the entire class of the stated securities from listing and registration on the Exchange at the opening of business on January 11, 2021, pursuant to the provisions of Rule 12d2-2 (a).

Hyliion 2020 Equity Incentive Plan, Form of Stock Option Agreement (incorporated by reference to Exhibit 99.3 to the Company’s Registration Statement on Form S-8 (File No. 333-251328) filed with the SEC on December 14, 2020).

Exhibit 99.3 Hyliion Holdings Corp. Form of Stock Option Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the “Company”), pursuant to its 2020 Equity Incentive Plan (the “Plan”), has granted to you (“Optionholder”) an option to purchase the number of shares of the Common Stock set forth below (the “Option”). Your Option is subject to all of the terms and conditions as set forth he

- REGISTRATION STATEMENT

As filed with the Securities and Exchange Commission on December 14, 2020 Registration No.

Hyliion 2020 Equity Incentive Plan, Form of RSU Award Agreement (incorporated by reference to Exhibit 99.4 to the Company’s Registration Statement on Form S-8 (File No. 333-251328) filed with the SEC on December 14, 2020).

Exhibit 99.4 Hyliion Holdings Corp. Form of RSU Award Grant Notice (2020 Equity Incentive Plan) Hyliion Holdings Corp. (the “Company”) has awarded to you (the “Participant”) the number of restricted stock units specified and on the terms set forth below in consideration of your services (the “RSU Award”). Your RSU Award is subject to all of the terms and conditions as set forth herein and in the C

Hyliion Inc. 2016 Equity Incentive Plan (incorporate by references to Exhibit 99.2 to the Company’s Registration Statement on Form S-8 (File No. 333-251328) filed with the SEC on December 14, 2020).

Exhibit 99.2 HYLIION INC. 2016 EQUITY INCENTIVE PLAN 1. Establishment, Purpose and Types of Awards Hyliion Inc., a Delaware corporation (the “Company”), hereby establishes the HYLIION INC. 2016 EQUITY INCENTIVE PLAN (the “Plan”). The purpose of the Plan is to promote the long-term growth and profitability of the Company by (i) providing key people with incentives to improve stockholder value and t

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): December 2, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Employment Agreement, dated December 2, 2020, by and between Hyliion Holdings Corp. and Patrick Sexton (incorporated by reference to Exhibit 10.2 to the Company’s Current Report on Form 8-K (File No. 001-38823) filed with the SEC on December 7, 2020).

Exhibit 10.2 EMPLOYMENT AGREEMENT This Employment Agreement (“Agreement”) is made and entered into by and between Hyliion Holdings Corp., a Delaware corporation, (the “Company”), and Patrick Sexton (“Employee”), and shall be effective as of the Effective Date, as defined below. This Agreement is intended to terminate and supersede any employment agreement, offer letter or other employment-related

Employment Agreement, dated December 2, 2020, by and between Hyliion Holdings Corp. and Thomas Healy (incorporated by reference to Exhibit 10.1 to the Company’s Current Report on Form 8-K (File No. 001-38823) filed with the SEC on December 7, 2020).

Exhibit 10.1 EMPLOYMENT AGREEMENT This Employment Agreement (“Agreement”) is made and entered into by and between Hyliion Holdings Corp., a Delaware corporation, (the “Company”), and Thomas J. Healy (“Employee”), and shall be effective as of the Effective Date, as defined below. This Agreement is intended to terminate and supersede any employment agreement, offer letter or other employment-related

NOTICE OF REDEMPTION OF CERTAIN WARRANTS (CUSIP 449109115)

Exhibit 99.2 November 30, 2020 NOTICE OF REDEMPTION OF CERTAIN WARRANTS (CUSIP 449109115) Dear Public Warrant Holder, Hyliion Holdings Corp. (the “Company”) hereby gives notice that it is redeeming, at 5:00 p.m. New York City time on December 30, 2020 (the “Redemption Date”), all of the Company’s outstanding warrants (the “Public Warrants”) to purchase shares of the Company’s common stock, $0.0001

Financial Statements and Exhibits, Other Events - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 30, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

Hyliion Announces Redemption of Public Warrants

Exhibit 99.1 Hyliion Announces Redemption of Public Warrants November 30, 2020 AUSTIN, Texas — Hyliion Holdings Corp. (NYSE: HYLN; HLYN WS) (“Hyliion”), a leader in electrified powertrain solutions for Class 8 commercial vehicles, today announced that holders of its approximately 12.5 million outstanding warrants (the “Public Warrants”) to purchase shares of its common stock, $0.0001 par value per

Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants

Filed Pursuant to Rule 424(b)(3) Registration No. 333-249649 PROSPECTUS Up to 132,637,517 Shares of Common Stock Up to 19,185,637 Shares of Common Stock Issuable Upon Exercise of Warrants Up to 7,555,183 Warrants This prospectus relates to the issuance by us of up to an aggregate of up to 19,185,637 shares of our common stock, $0.0001 par value per share (“Common Stock”), which consists of (i) up

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HYLIION HOLDINGS CORP. 1202 BMC Drive, Suite 100 Cedar Park, Texas 78613 November 24, 2020 Division of Corporation Finance Office of Manufacturing United States Securities and Exchange Commission 100 F Street, N.E. Washington, D.C. 20549 RE: Hyliion Holdings Corp. Registration Statement on Form S-1 File No. 333-249649 Ladies and Gentlemen: Hyliion Holdings Corp. (the “Registrant”) hereby requests

- REGISTRATION STATEMENT

S-1/A 1 fs12020a1hyliionholdings.htm REGISTRATION STATEMENT As filed with the Securities and Exchange Commission on November 23, 2020 Registration No. 333-249649 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 1 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Hyliion Holdings Corp. (Exact Name of Registrant as Specified in its Charter) Dela

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November 23, 2020 Division of Corporation Finance Office of Manufacturing United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

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CORRESP 1 filename1.htm November 20, 2020 Division of Corporation Finance Office of Manufacturing United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, D.C. 20549-3561 Re: Hyliion Holdings Corp. Registration Statement on Form S-1 Filed on October 23, 2020 File No. 333-249649 Ladies and Gentlemen: Set forth below are the proposed responses o

The accompanying notes are an integral part of these unaudited condensed financial statements

Exhibit 99.1 Hyliion Inc. Condensed Balance Sheets (Dollar amounts in thousands, except share and per share data) (Unaudited) September 30, 2020 December 31, 2019 Assets: Current assets: Cash and cash equivalents $ 7,565 $ 6,285 Accounts receivable, net 15 145 Prepaid expenses and other current assets 1,085 414 Total current assets 8,665 6,844 Property and equipment, net 1,126 1,635 Operating leas

MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS OF HYLIION

Exhibit 99.2 MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS OF HYLIION The following discussion and analysis provides information that our management believes is relevant to an assessment and understanding of our results of operations and financial condition. This discussion and analysis should be read together with the unaudited financial statements and rela

Financial Statements and Exhibits - AMENDMENT NO.2 TO CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A (Amendment No. 2) CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 12, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incor

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

Exhibit 99.3 UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION The following unaudited pro forma condensed combined financial statements of Hyliion Holdings Corp. (f/k/a Tortoise Acquisition Corp.). (“Tortoise”) present the combination of the financial information of Tortoise and Hyliion Inc. (“Hyliion”) adjusted to give effect to the merger of Hyliion with and into a wholly-owned subsi

Quarterly Report - QUARTERLY REPORT

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2020 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File No. 001-38823 HYLIION HOLDINGS COR

Hyliion Reports Third Quarter 2020 Financial Results

Exhibit 99.1 INVESTOR INQUIRIES Bob Gujavarty Hyliion Holdings [email protected] MEDIA RELATIONS Mustafa Riffat [email protected] Jeremy Cohen [email protected] Edelman Hyliion Reports Third Quarter 2020 Financial Results AUSTIN, Texas (Nov. 12, 2020)—Hyliion Holdings Corp. (NYSE: HYLN) (“Hyliion Holdings”), a leader in electrified powertrain solutions for Class 8 commercial vehicles,

Results of Operations and Financial Condition, Financial Statements and Exhibits - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 12, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commissio

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 23, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction of Incorporation) (Commission

Form S-1

As filed with the Securities and Exchange Commission on October 23, 2020 Registration No.

List of Subsidiaries

Exhibit 21.1 Subsidiaries of Hyliion Holdings Corp. Name of Subsidiary Jurisdiction of Organization Hyliion Inc. Delaware

Employment Agreement, dated October 23, 2020, by and between the Company and Greg Van de Vere (incorporated by reference to Exhibit 10.7 to the Company’s Registration Statement on Form S-1 (File No. 333-249649) filed with the SEC on October 23, 2020).

Exhibit 10.7 EMPLOYMENT AGREEMENT This Employment Agreement (“Agreement”) is made and entered into by and between Hyliion Holdings Corp., a Delaware corporation, (the “Company”), and Greg Van de Vere (“Employee”) effective as of the Effective Date, as defined below. This Agreement is intended to terminate and supersede any employment agreement, offer letter or other employment-related agreement by

HYLN / Hyliion Holdings Corp. / Grace Victoria K. - SC 13G Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 Hyliion Holdings Corp. (Name of Issuer) (Common Stock, $0.0001 par value per share) 449109107 (CUSIP Number) October 1, 2020 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: ☐

SHLL / Tortoise Acquisition Corp. / FJ Management Inc. - SC 13G Passive Investment

SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 Hyliion Holdings Corp. (Name of Issuer) (Common Stock, $0.0001 par value per share) 449109107 (CUSIP Number) October 1, 2020 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is fi

Form of Lock-Up Agreement, dated October 1, 2020.

October 1, 2020 Hyliion Holdings Corp. 1202 BMC Drive Cedar Park, TX 78613 Re: Lock-Up Agreement Ladies and Gentlemen: This letter (this “Letter Agreement”) is being delivered to you in accordance with the Business Combination Agreement and Plan of Reorganization (the “BCA”) entered into by and among Hyliion Holdings Corp., a Delaware corporation f/k/a Tortoise Acquisition Corp. (the “Company”), S

Amended and Restated Registration Rights Agreement, dated October 1, 2020.

AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT THIS AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT (this “Agreement”), dated as of October 1, 2020, is made and entered into by and among Hyliion Holdings Corp.

Joint Filing Agreement, dated October 13, 2020.

EXHIBIT 1 JOINT FILING AGREEMENT In accordance with Rule 13d-1(k) of the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a Statement on Schedule 13D (including any and all amendments thereto) with respect to the shares of common stock, par value $0.

SHLL / Tortoise Acquisition Corp. / AXIOMA VENTURES, LLC Activist Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. )* HYLIION HOLDINGS CORP. (Name of Issuer) Common Stock, par value $0.0001 per share (Title of Class of Securities) 449109 107 (CUSIP Number) Howard M. Jenkins c/o Axioma Management, LLC 601 South Boulevard Tampa, Florida 33606 (813) 760-2229 (Name, Address

SHLL / Tortoise Acquisition Corp. / Healy Thomas J. - SC 13D Activist Investment

SC 13D UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D UNDER THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No. )* Hyliion Holdings Corp. (Name of Issuer) Common Stock (Title of Class of Securities) 449109107 (CUSIP Number) Thomas J. Healy 1202 BMC Drive, Suite 100 Cedar Park, Texas 78613 Telephone: (833) 495-4466 (Name, Address and Telephone Number of Person A

Form of Common Stock Certificate of the Company (incorporated by reference to Exhibit 4.1 to the Current Report on Form 8-K filed on October 7, 2020).

Exhibit 4.1 [Form of Common Stock Certificate] NUMBER C- SHARES SEE REVERSE FOR CERTAIN DEFINITIONS CUSIP 449109 107 HYLIION HOLDINGS CORP. INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE COMMON STOCK This Certifies that is the owner of FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK, PAR VALUE OF $0.0001 OF HYLIION HOLDINGS CORP. (THE “CORPORATION”) transferable on the books of the Corp

Offer Letter, dated May 22, 2019, by and between Hyliion Inc. and Patrick Sexton (incorporated by reference to Exhibit 10.8 to the Current Report on Form 8-K filed on October 7, 2020).

EX-10.8 13 ea127824ex10-8hyliionhold.htm OFFER LETTER, DATED MAY 22, 2019, BY AND BETWEEN HYLIION INC. AND PATRICK SEXTON Exhibit 10.8 1202 BMC Dr. Cedar Park, TX 78613 May 22, 2019 Patrick Sexton Dear Patrick: On behalf of Hyliion Inc. (the “Company”), we are pleased to offer you the full-time position of Vice President of Hardware. In your role as Vice President of Hardware, you will report dire

Letter from WithumSmith+Brown, PC to the SEC, dated October 1, 2020 (incorporated by reference to Exhibit 16.1 to the Company’s Current Report on Form 8-K (File No. 001-38823) filed with the SEC on October 7, 2020).

Exhibit 16.1 October 1, 2020 Office of the Chief Accountant Securities and Exchange Commission 100 F Street, NE Washington, D.C. 20549 Ladies and Gentlemen: We have read Hyliion Holdings Corp. statements (formally known as Tortoise Acquisition Corp.) included under Item 4.01 of its Form 8-K dated October 1, 2020. We agree with the statements concerning our Firm under Item 4.01, in which we were in

Executive Employment Agreement, dated March 29, 2019, by and between Hyliion Inc. and Greg Van de Vere.

Exhibit 10.7 Hyliion Inc. EXECUTIVE EMPLOYMENT AGREEMENT This EMPLOYMENT AGREEMENT (the “Agreement”) is effective as of March 29, 2019 by and between Hyliion Inc., a Delaware corporation (the “Company”), and Greg Van de Vere (“Executive”). RECITALS WHEREAS, the Company designs hybrid drive systems for Class 8 Semi Tractors and related and derivative products; and WHEREAS, the Company desires to re

Form of Lock-Up Agreement (incorporated by reference to Exhibit 4.5 to the Current Report on Form 8-K filed on October 7, 2020).

EX-4.5 7 ea127824ex4-5hyliionhold.htm FORM OF LOCK-UP AGREEMENT Exhibit 4.5 October 1, 2020 Hyliion Holdings Corp. 1202 BMC Drive Cedar Park, TX 78613 Re: Lock-Up Agreement Ladies and Gentlemen: This letter (this “Letter Agreement”) is being delivered to you in accordance with the Business Combination Agreement and Plan of Reorganization (the “BCA”) entered into by and among Hyliion Holdings Corp.

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Amendment to Registrant's Code of Ethics, or Waiver of a Provision of the Code of Ethics, Financial Statements and Exhibits - AMENDMENT NO. 1 TO FORM 8-K

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K/A (Amendment No.1) CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 1, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction (Commission

Second Amended and Restated Certificate of Incorporation of the Company, dated October 1, 2020 (incorporated by reference to Exhibit 3.1 to the Company’s Current Report on Form 8-K (File No. 001-38823) filed with the SEC on October 7, 2020).

Exhibit 3.1 SECOND AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF TORTOISE ACQUISITION CORP. Vincent T. Cubbage hereby certifies that: ONE: The name of this company is Tortoise Acquisition Corp. and the date of filing the original Certificate of Incorporation of this corporation with the Secretary of State of Delaware was November 7, 2018. TWO: Vincent T. Cubbage is the duly elected and acti

Lock-Up Agreement, dated October 1, 2020, by and between the Company and Thomas Healy (incorporated by reference to Exhibit 4.6 to the Company’s Current Report on Form 8-K (File No. 001-38823) filed with the SEC on October 7, 2020).

Exhibit 4.6 October, 1 2020 Hyliion Holdings Corp. 1202 BMC Drive Cedar Park, TX 78613 Re: Lock-Up Agreement Ladies and Gentlemen: This letter (this “Letter Agreement”) is being delivered to you in accordance with the Business Combination Agreement and Plan of Reorganization (the “BCA”) entered into by and among Hyliion Holdings Corp., a Delaware corporation f/k/a Tortoise Acquisition Corp. (the “

Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Entry into a Material Definitive Agreement, Unregistered Sales of Equity Securities, Financial Statements and Exhibits, Changes in Registrant's Certifying Accountant, Completion of Acquisition or Disposition of Assets, Material Modification to Rights of Security Holders, Changes in Control of Registrant, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Change in Shell Company Status - CURRENT REPORT

united states SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): October 1, 2020 Hyliion Holdings Corp. (Exact name of registrant as specified in its charter) Delaware 001-38823 82-2538002 (State or Other Jurisdiction (Commission File Number) (I.R.