Statement of Changes in Beneficial Ownership (4)

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 OF SECURITIES

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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * OLKKOLA EDWARD E	2. Issuer Name and Ticker or Trading Symbol Hyliion Holdings Corp. [ HYLN ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                    _____ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) 1202 BMC DRIVE, SUITE 100	3. Date of Earliest Transaction (MM/DD/YYYY) 6/2/2021
(Street) CEDAR PARK, TX 78613 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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	6/2/2021		M		100000	A	$0.086	831610	D
Common Stock								166560	I	By Spouse

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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
Stock Option (Right to Buy)	$0.086	6/2/2021		M			100000	(1)	8/28/2026	Common Stock	100000.0	(2)	892901	D

Explanation of Responses:
(1)	The option became exercisable in equal quarterly installments over 4 years beginning on August 29, 2016.
(2)	The option was received in exchange for an option to purchase 750,000 shares of Hyliion Inc. ("Legacy Hyliion") common stock pursuant to the Business Combination Agreement and Plan of Reorganization, dated as of June 18, 2020, by and among Tortoise Acquisition Corp. ("Tortoise"), Legacy Hyliion and SHLL Merger Sub Inc., a wholly-owned subsidiary of Tortoise ("Merger Sub"), pursuant to which Merger Sub merged with and into Legacy Hyliion, with Legacy Hyliion surviving the merger as a wholly-owned subsidiary of Tortoise (which subsequently changed its name to "Hyliion Holdings Corp.").

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
OLKKOLA EDWARD E 1202 BMC DRIVE SUITE 100 CEDAR PARK, TX 78613	X

Signatures
/s/ Edward E. Olkkola		6/2/2021
**Signature of Reporting Person		Date