Hyliion (HYLN) CTO receives 540,541 RSUs under 2024 plan, shares withheld for taxes

Rhea-AI Filing Summary

Hyliion Holdings Corp. reported an equity transaction involving its Chief Technology Officer, who is an officer of the company and filed individually. On November 26, 2025, the officer acquired 540,541 shares of common stock at $1.85 per share, recorded as an acquisition of securities. Following this transaction, the officer beneficially owned 1,048,113 shares directly.

The filing explains that this reflects a grant of restricted stock units under Hyliion’s 2024 Equity Incentive Plan. One-fifth of the award will vest on November 26, 2026, one-fifth on November 26, 2027, and three-fifths on November 26, 2028. On November 27, 2025, 1,361 shares were disposed of at $1.85 per share, representing shares withheld to cover tax liabilities related to vesting and distribution, leaving 1,046,752 shares beneficially owned directly.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

MOOK JOSHUA T.

(Last) (First) (Middle)

C/O HYLIION HOLDING CORP.

1202 BMC DRIVE, SUITE 100

(Street)

CEDAR PARK TX 78613

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Hyliion Holdings Corp. [ HYLN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Technology Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/26/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

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. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	11/26/2025		A(1)		540,541	A	$1.85	1,048,113	D
Common Stock	11/27/2025		F(2)		1,361	D	$1.85	1,046,752	D

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		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: 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

Explanation of Responses:

1. The Reporting Person received a grant of restricted stock units ("RSU Award") pursuant to the Issuer's 2024 Equity Incentive Plan. One-fifth (1/5) of the RSU Award will vest on November 26, 2026, one-fifth (1/5) of the RSU Award will vest on November 26, 2027, and three-fifths (3/5) of the RSU Award will vest on November 26, 2028.

2. Shares withheld for the payment of a tax liability related to the vesting and distribution of restricted stock units.

Remarks:

	/s/ Joshua T. Mook	12/01/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What insider transaction did Hyliion (HYLN) report in this Form 4?

The filing reports that Hyliion’s Chief Technology Officer acquired 540,541 shares of common stock on November 26, 2025 at $1.85 per share, and that this transaction increased his directly beneficially owned shares to 1,048,113 before a subsequent tax-related share withholding.

How many Hyliion (HYLN) shares does the reporting officer own after the reported transactions?

After the transactions reported in the Form 4, including the tax withholding, the officer directly beneficially owned 1,046,752 shares of Hyliion common stock.

What is the vesting schedule for the Hyliion (HYLN) restricted stock unit award?

The restricted stock unit award vests in three stages: one-fifth on November 26, 2026, one-fifth on November 26, 2027, and three-fifths on November 26, 2028, under Hyliion’s 2024 Equity Incentive Plan.

Why were 1,361 Hyliion (HYLN) shares disposed of on November 27, 2025?

The 1,361 shares of Hyliion common stock disposed of on November 27, 2025 at $1.85 per share were shares withheld for payment of a tax liability related to the vesting and distribution of restricted stock units.

What role does the reporting person hold at Hyliion (HYLN)?

The reporting person is an officer of Hyliion Holdings Corp., serving as the company’s Chief Technology Officer, as indicated in the relationship section of the filing.

Under which plan were the Hyliion (HYLN) restricted stock units granted?

The restricted stock units were granted to the officer pursuant to Hyliion’s 2024 Equity Incentive Plan, as described in the explanation of responses.