Sec Form 4 Filing - Tortoise Sponsor LLC @ Hyliion Holdings Corp. - 2020-10-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Tortoise Sponsor LLC 2. Issuer Name and Ticker or Trading Symbol Hyliion Holdings Corp. [ HYLN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 5100 W. 115TH PLACE 3. Date of Earliest Transaction (MM/DD/YY) 10/01/2020 (Street) LEAWOOD, KS66211 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 10/01/2020 C 4,439,605 A 4,439,605 D ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Class B Common Stock ( 1 ) 10/01/2020 C 4,439,605 ( 3 ) ( 3 ) Class A Common Stock 4,439,605 ( 1 ) 0 D ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Tortoise Sponsor LLC 5100 W. 115TH PLACE LEAWOOD, KS66211 X TortoiseEcofin Borrower LLC 5100 W. 115TH PLACE LEAWOOD,, KS66211 X TortoiseEcofin Investments, LLC 5100 W. 115TH PLACE LEAWOOD,, KS66211 X Signatures /s/ Tortoise Sponsor LLC, by Vincent T. Cubbage as Attorney-in-Fact 10/05/2020 Signature of Reporting Person Date /s/ TortoiseEcofin Borrower LLC, by Vincent T. Cubbage as Attorney-in-Fact 10/05/2020 Signature of Reporting Person Date /s/ TortoiseEcofin Investments, LLC, Vincent T. Cubbage as Attorney-in-Fact 10/05/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )In connection with the closing of the business combination between Tortoise Acquisition Corp. ("TortoiseCorp"), SHLL Merger Sub and Hyliion Inc. on October 1, 2020, the Reporting Person's shares of Class B Common Stock automatically converted into shares of TortoiseCorp's Class A Common Stock on a one-for-one basis. Upon consummation of the business combination, TortoiseCorp changed its name to "Hyliion Holdings Corp." and all outstanding shares of Class A Common Stock were automatically reclassified, redesignated and changed into one share of Hyliion Holdings Corp. Common Stock. ( 2 )Tortoise Sponsor LLC is the record holder of the shares reported herein. TortoiseEcofin Borrower LLC is the managing member of Tortoise Sponsor LLC. TortoiseEcofin Parent Holdco LLC is the sole member of TortoiseEcofin Borrower LLC, and TortoiseEcofin Investments, LLC is the sole member of TortoiseEcofin Parent Holdco LLC. Accordingly, TortoiseEcofin Borrower LLC and TortoiseEcofin Investments, LLC may be deemed to have or share beneficial ownership of the shares of Class B Common Stock held directly by Tortoise Sponsor LLC. The address of each of TortoiseEcofin Borrower LLC and TortoiseEcofin Investments, LLC is 5100 W. 115th Place, Leawood, Kansas 66211. ( 3 )The shares of Class B Common Stock are automatically convertible into shares of Class A Common Stock at the time of TortoiseCorp's initial business combination on a one-for-one basis, subject to adjustment pursuant to certain anti-dilution rights, and have no expiration date.

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