LAB insider reports 19,661-share tax withholding, 779,835 shares owned

Rhea-AI Filing Summary

Standard BioTools Inc. (LAB) executive Sean Mackay, SVP & Chief Business Officer, reported a routine equity transaction on Form 4. On 11/20/2025, 19,661 shares of common stock were withheld at a price of $1.28 per share, indicated by transaction code "F," to cover tax obligations arising from the vesting of previously granted restricted stock units. After this tax withholding, Mackay beneficially owns 779,835 shares of Standard BioTools common stock 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^*

Mackay Sean

(Last) (First) (Middle)

C/O STANDARD BIOTOOLS INC.

2 TOWER PLACE, STE 2000

(Street)

SOUTH SAN FRANCISCO CA 94080

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
STANDARD BIOTOOLS INC. [ LAB ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP & Chief Business Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/20/2025

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	11/20/2025		F		19,661(1)	D	$1.28	779,835	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 shares were withheld from the reporting person to satisfy the tax withholding obligations that arose upon the vesting of restricted stock units granted to the reporting person on May 20, 2024 and March 21, 2025, which grants were originally reported on Form 3 and Form 4 filed with the U.S. Securities and Exchange Commission on September 3, 2024 and March 24, 2025, respectively.

	/s/ Sean Mackay by Tomone Tanaka, Attorney-in-Fact	11/24/2025
	** 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).
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 STANDARD BIOTOOLS INC. (LAB) report on this Form 4?

The filing reports that 19,661 shares of Standard BioTools common stock were withheld on 11/20/2025 to satisfy tax obligations from vested restricted stock units.

Who is the reporting person in this STANDARD BIOTOOLS INC. (LAB) Form 4?

The reporting person is Sean Mackay, who serves as SVP & Chief Business Officer of Standard BioTools Inc.

What was the price used for the share withholding in the LAB Form 4?

The 19,661 withheld shares of Standard BioTools common stock were valued at $1.28 per share for the tax withholding transaction.

How many STANDARD BIOTOOLS INC. (LAB) shares does the insider own after this transaction?

Following the reported tax withholding transaction, the reporting person beneficially owns 779,835 shares of Standard BioTools common stock directly.

What does transaction code "F" mean in this STANDARD BIOTOOLS INC. (LAB) Form 4?

Transaction code "F" indicates shares were withheld to pay taxes due upon the vesting of equity awards, in this case restricted stock units.

Which equity awards led to the tax withholding in this LAB Form 4?

The tax withholding arose from the vesting of restricted stock units granted to the reporting person on May 20, 2024 and March 21, 2025.