As filed with the Securities and Exchange Commission on July 8, 2021 Registration No. 333-249649 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 POST-EFFECTIVE 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) Delaware 3713 83-2538002 (State or Other Jurisdiction of (Primary Standard Industrial (I.R.S. Employer Incorporation or Organization) Classification Code No.) Identification No.) 1202 BMC Drive, Suite 100 Cedar Park, Texas 78613 Tel: (833) 495-4466 (Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices) Thomas Healy Chief Executive Officer Hyliion Holdings Corp. 1202 BMC Drive, Suite 100 Cedar Park, Texas 78613 Tel: (833) 495-4466 (Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service) Copies to: Brenda K. Lenahan Vinson & Elkins L.L.P. 1114 6th Avenue, 32nd Floor New York, New York 10036 Tel: (212) 237-0000 Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement. If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box. ☒ If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 under the Securities Exchange Act of 1934: Large accelerated filer ☐ Accelerated filer ☐ Non-accelerated filer ☒ Smaller reporting company ☒ Emerging growth company ☒ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐ The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment that specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine. EXPLANATORY NOTE On October 23, 2020, Hyliion Holdings Corp (the “Company”) filed a registration statement with the Securities and Exchange Commission (the “SEC”) on Form S-1 (File No. 333-249649) (the “Registration Statement”). The Registration Statement, as amended, was initially declared effective by the SEC on November 27, 2020 and initially registered the issuance by the Company of up to an aggregate of up to 19,185,637 shares of common stock, $0.0001 par value per share (“Common Stock”), which consisted of (i) up to 6,660,183 shares of Common Stock issuable upon the exercise of 6,660,183 warrants (the “Private Placement Warrants”) originally issued in a private placement in connection with the initial public offering of Tortoise Acquisition Corp. (“TortoiseCorp”) by the holders thereof, (ii) up to 875,000 shares of Common Stock that are issuable upon the exercise of 875,000 warrants (the “Forward Purchase Warrants” and together with the Private Placement Warrants, the “Private Warrants”) originally issued in a private placement at the closing of the Business Combination (as defined below) by the holders thereof other than the initial holder and (iii) up to 11,650,454 shares of Common Stock issuable upon the exercise of 11,650,454 warrants (the “Public Warrants” and, together with the Private Warrants, the “Warrants”) originally issued in the initial public offering of TortoiseCorp by the holders thereof. The Registration Statement also initially registered the offer and sale from time to time by the selling stockholders identified in the prospectus of (i) up to 132,637,517 shares of Common Stock (including up to 7,535,183 shares of Common Stock that may be issued upon exercise of the Private Warrants and 20,000 shares of Common Stock that may be issued upon exercise of 20,000 Public Warrants) and (ii) up to 7,555,183 Warrants, which consists of up to 7,535,183 Private Warrants and up to 20,000 Public Warrants. This Post-Effective Amendment No. 1 to Form S-1 (“Post-Effective Amendment No. 1”) is being filed by the Company to update the Registration Statement to (i) remove references to the registration of the Warrants and the shares of Common Stock to be issued upon exercise thereof to reflect the redemption or exercise of all Warrants on or before December 31, 2020; (ii) include updated information regarding the selling stockholders named in the prospectus, including a reduction in the number of shares of Common Stock being offered by the selling stockholders to 91,394,533 shares of Common Stock and (iii) include the information from the Company’s filings with the SEC. No additional securities are being registered under this Post-Effective Amendment No. 1. All applicable registration fees were paid at the time of the original filing of the Registration Statement. The information in this preliminary prospectus is not complete and may be changed. Neither we nor the selling securityholders may sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities and is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted. SUBJECT TO COMPLETION — DATED JULY 8, 2021 PRELIMINARY 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 Securityholders pursuant to this prospectus. Our registration of the securities covered by this prospectus does not mean that the Selling Securityholders will offer or sell any of the shares of Common Stock. The Selling Securityholders may offer, sell or distribute all or a portion of their shares of Common Stock publicly or through private transactions at prevailing market prices or at negotiated prices. We provide more information about how the Selling Securityholders may sell the shares in the section entitled “Plan of Distribution.” We are an “emerging growth company” as defined in Section 2(a) of the Securities Act of 1933, as amended, and are subject to reduced public company reporting requirements. This prospectus complies with the requirements that apply to an issuer that is an emerging growth company. Our Common Stock is listed on the New York Stock Exchange (the “NYSE”) under the symbol “HYLN”. On July 7, 2021, the closing price of our Common Stock was $10.78. See the section entitled “Risk Factors” beginning on page 6 of this prospectus to read about factors you should consider before buying our securities. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense. The date of this prospectus is , 2021. TABLE OF CONTENTS Page ABOUT THIS PROSPECTUS ii CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS iii SUMMARY 1 THE OFFERING 5 RISK FACTORS 6 USE OF PROCEEDS 31 DETERMINATION OF OFFERING PRICE 32 MARKET INFORMATION FOR COMMON STOCK AND DIVIDEND POLICY 33 UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION 34 MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS 38 BUSINESS 50 MANAGEMENT 63 EXECUTIVE COMPENSATION 71 CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS 76 PRINCIPAL SECURITYHOLDERS 80 SELLING SECURITYHOLDERS 82 DESCRIPTION OF OUR SECURITIES 87 PLAN OF DISTRIBUTION 91 LEGAL MATTERS 93 EXPERTS 93 WHERE YOU CAN FIND MORE INFORMATION 93 INDEX TO FINANCIAL STATEMENTS F-1 You should rely only on the information provided in this prospectus, as well as the information incorporated by reference into this prospectus and any applicable prospectus supplement. Neither we nor the Selling Securityholders have authorized anyone to provide you with different information. Neither we nor the Selling Securityholders are making an offer of these securities in any jurisdiction where the offer is not permitted. You should not assume that the information in this prospectus or any applicable prospectus supplement is accurate as of any date other than the date of the applicable document. Since the date of this prospectus and the documents incorporated by reference into this prospectus, our business, financial condition, results of operations and prospects may have changed. i ABOUT THIS PROSPECTUS This prospectus is part of a registration statement on Form S-1 that we filed with the SEC using the “shelf” registration process.