Joshua T. Mook - 26 Nov 2025 Form 4 Insider Report for Hyliion Holdings Corp. (HYLN)

Role: Chief Technology Officer
Signature: /s/ Joshua T. Mook
Issuer symbol: HYLN
Transactions as of: 26 Nov 2025
Net transactions value: +$997,483
Form type: 4
Filing time: 01 Dec 2025, 17:43:58 UTC
Previous filing: 17 Nov 2025
Next filing: 15 Dec 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
MOOK JOSHUA T.	Chief Technology Officer	C/O HYLIION HOLDING CORP., 1202 BMC DRIVE, SUITE 100, CEDAR PARK	/s/ Joshua T. Mook	01 Dec 2025	0002011297

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	HYLN	Common Stock	Award	$1,000,001	+540,541	+106%	$1.85	1,048,113	26 Nov 2025	Direct	F1
transaction	HYLN	Common Stock	Tax liability	$2,518	-1,361	-0.13%	$1.85	1,046,752	27 Nov 2025	Direct	F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	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.
F2	Shares withheld for the payment of a tax liability related to the vesting and distribution of restricted stock units.