Hyliion (HYLN) CTO has shares sold to cover equity award taxes

Rhea-AI Filing Summary

Hyliion Holdings Corp. reported an insider transaction involving Chief Technology Officer Joshua T. Mook. On this Form 4, 14,816 shares of common stock were sold at $2.04 per share to cover his tax withholding obligations under an equity award. According to the award agreement, the decision to sell these shares was made at the sole discretion of the issuer. After this transaction, Mook directly owned 1,114,109 shares of Hyliion common stock.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider MOOK JOSHUA T.

Role Chief Technology Officer

Type	Security	Shares	Price	Value
Other	Common Stock	14,816	$2.04	$30K

Holdings After Transaction: Common Stock — 1,114,109 shares (Direct)

Footnotes (1)

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Form 4 Insider Transactions: What Each Field Means →

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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)
03/03/2026

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	03/03/2026		J(1)		14,816	D	$2.04	1,114,109	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. These shares were sold at the direction of the issuer under the terms of the issuer's award agreement with the reporting person. Under the award agreement, the decision to sell shares to cover the reporting person's tax withholding obligations is at the sole discretion of the issuer.

Remarks:

	/s/ Joshua T. Mook	03/04/2026
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Hyliion (HYLN) report for Joshua T. Mook?

Hyliion reported that Chief Technology Officer Joshua T. Mook had 14,816 shares of common stock sold. The transaction was linked to his equity award and handled under the issuer’s award agreement to address related tax obligations.

At what price were the Hyliion (HYLN) shares sold in Joshua Mook’s Form 4?

The 14,816 Hyliion common shares were sold at $2.04 per share. This price applied to the shares disposed of to satisfy tax withholding requirements associated with Joshua Mook’s equity award from the company.

Why were Joshua T. Mook’s Hyliion (HYLN) shares sold in this transaction?

The shares were sold to cover tax withholding obligations tied to Joshua Mook’s equity award. The filing notes that under the award agreement, the issuer alone decided to sell shares for this tax withholding purpose.

Who decided to sell the Hyliion (HYLN) shares reported in Joshua Mook’s Form 4?

The filing states the shares were sold at the direction of the issuer. Under the award agreement, the issuer has sole discretion to sell shares needed to cover the reporting person’s tax withholding obligations from the equity award.

How many Hyliion (HYLN) shares does Joshua T. Mook hold after this Form 4 transaction?

After the reported transaction, Chief Technology Officer Joshua T. Mook directly held 1,114,109 shares of Hyliion common stock. This figure reflects his direct ownership following the tax-related share sale.

What does transaction code J mean in Joshua Mook’s Hyliion (HYLN) Form 4?

Transaction code J on the Form 4 represents an “other acquisition or disposition” of securities. In this case, it refers to shares sold under the issuer’s award agreement specifically to satisfy tax withholding obligations.