[Form 4] COMFORT SYSTEMS USA INC Insider Trading Activity

Rhea-AI Filing Summary

Comfort Systems USA chief executive and director Brian E. Lane reported equity compensation activity in the company’s common stock. On March 23, 2026, he received a grant of 2,876 restricted stock units, each representing one future share and vesting in equal installments over three years. On the same date, 2,312 dollar‑denominated performance restricted stock units granted in 2023 vested based on the company’s 2023–2025 relative total shareholder return and average EPS. To cover tax obligations, 910 shares were withheld at a price of 1408.25 per share. After these transactions, Lane directly owned 175,801 shares of common stock.

Insider Trade Summary

3 transactions reported

Mixed 3 txns

Insider Lane Brian E.

Role CHIEF EXECUTIVE OFF.

Type	Security	Shares	Price	Value
Grant/Award	Common Stock	2,876	$0.00	--
Grant/Award	Common Stock	2,312	$0.00	--
Tax Withholding	Common Stock	910	$1,408.25	$1.28M

Holdings After Transaction: Common Stock — 174,399 shares (Direct)

Footnotes (1)

1. Each restricted stock unit granted on March 23, 2026 represents a right to receive one share of common stock and will vest in equal installments over a three-year vesting schedule. Reflects dollar-denominated performance restricted stock units granted on March 21, 2023 that vested on March 23, 2026. These units vested as a result of the Company's 2023-2025 relative Total Shareholder Return and 2023-2025 Company average EPS, which are the applicable performance measures. Forfeited shares are related to dollar-denominated performance restricted stock units that vested on March 23, 2026 and were priced based on the closing price of the Company common stock on March 23, 2026.

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
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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^*

Lane Brian E.

(Last) (First) (Middle)

C/O COMFORT SYSTEMS USA, INC.

9753 KATY FREEWAY, SUITE 700

(Street)

HOUSTON TEXAS 77024

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
COMFORT SYSTEMS USA INC [ FIX ]

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

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CHIEF EXECUTIVE OFF.

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/23/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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

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	03/23/2026		A		2,876(1)	A	$0	174,399	D
Common Stock	03/23/2026		A		2,312(2)	A	$0	176,711	D
Common Stock	03/23/2026		F		910(3)	D	$1,408.25	175,801	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. Each restricted stock unit granted on March 23, 2026 represents a right to receive one share of common stock and will vest in equal installments over a three-year vesting schedule.

2. Reflects dollar-denominated performance restricted stock units granted on March 21, 2023 that vested on March 23, 2026. These units vested as a result of the Company's 2023-2025 relative Total Shareholder Return and 2023-2025 Company average EPS, which are the applicable performance measures.

3. Forfeited shares are related to dollar-denominated performance restricted stock units that vested on March 23, 2026 and were priced based on the closing price of the Company common stock on March 23, 2026.

	/s/ Rachel R. Eslicker, Attorney-in-Fact	03/25/2026
	** 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.
* Form 4: SEC 1474 (03-26)