[Form 4] STANDARD BIOTOOLS INC. Insider Trading Activity

Rhea-AI Filing Summary

Standard BioTools (LAB) reported insider open‑market purchases by entities affiliated with Eli Casdin. The filing lists four buys totaling 1,175,000 shares on 11/07 (225,000 at a weighted average $1.1234), 11/10 (275,000 at $1.1706), 11/11 (300,000 at $1.196), and 11/12/2025 (375,000 at $1.1889).

Following these transactions, the Master Fund’s indirectly beneficially owned balance is stated as 62,050,000 shares. Additional positions reported include 2,901,062 shares held directly by Eli Casdin, 13,939,637 shares indirectly by Casdin Private Growth Equity Fund II, L.P., and 2,744,219 shares indirectly by Casdin Private Growth Equity Fund, L.P. The form is filed by more than one reporting person and marks the reporting persons as a director and 10% owner.

Insights

Equity Ownership Analyst

Insider group increased stake via four open-market buys; no sales or derivatives reported.

STANDARD BIOTOOLS INC. (LAB) reported open-market purchases by entities affiliated with Eli Casdin, a director and 10% owner. The group bought 1,175,000 shares across four dates: 11/07/2025 ($1.1234 WA), 11/10/2025 ($1.1706 WA), 11/11/2025 ($1.196 WA), and 11/12/2025 ($1.1889 WA). The Master Fund’s indirect holdings rose sequentially to 62,050,000 shares after the last trade.

No derivative transactions were reported. Additional positions disclosed include 2,901,062 shares held directly by Eli Casdin and indirect holdings of 13,939,637 (Equity Fund II) and 2,744,219 (Equity Fund). The filing is a joint submission by multiple affiliated entities, with “director by deputization” noted, and standard beneficial ownership disclaimers applied.

This signals increased insider exposure without offsetting sales. Items to watch: subsequent Form 4s for continued accumulation, any Form 13D/13G amendments reflecting aggregate changes, and updates to indirect holdings attribution. Near term, monitor filings following 11/12/2025 to assess whether buying persists.

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^*

Casdin Partners Master Fund, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
11/07/2025

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

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

	Form filed by One Reporting Person
X	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, $0.001 par value per share	11/07/2025		P		225,000	A	$1.1234(1)	61,100,000	I	See Footnote(5)
Common Stock, $0.001 par value per share	11/10/2025		P		275,000	A	$1.1706(2)	61,375,000	I	See Footnote(5)
Common Stock, $0.001 par value per share	11/11/2025		P		300,000	A	$1.196(3)	61,675,000	I	See Footnote(5)
Common Stock, $0.001 par value per share	11/12/2025		P		375,000	A	$1.1889(4)	62,050,000	I	See Footnote(5)
Common Stock, $0.001 par value per share								2,901,062	D(6)
Common Stock, $0.001 par value per share								13,939,637	I	See Footnote(7)
Common Stock, $0.001 par value per share								2,744,219	I	See Footnote(8)

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

1. Name and Address of Reporting Person^*

Casdin Partners Master Fund, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Eli

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Capital, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Private Growth Equity Fund II, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Partners GP, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Private Growth Equity Fund II GP, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS, SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Casdin Private Growth Equity Fund, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

CASDIN PRIVATE GROWTH EQUITY FUND GP, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.1153 to $1.1321. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote.

2. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.1688 to $1.1732. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote.

3. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.1881 to $1.2053. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote.

4. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.1865 to $1.1913. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote.

5. The securities are owned directly by Casdin Partners Master Fund, L.P. (the "Master Fund") and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC ("Casdin"), the investment adviser to the Master Fund, (ii) Casdin Partners GP, LLC (the "GP"), the general partner of the Master Fund, and (iii) Eli Casdin, the managing member of Casdin and the GP.

6. The securities are owned directly by Eli Casdin.

7. The securities are owned directly by Casdin Private Growth Equity Fund II, L.P. (the "Equity Fund II") and may be deemed to be indirectly beneficially owned by (i) Casdin, the investment adviser to the Equity Fund II, and (ii) Eli Casdin, the managing member of Casdin.

8. The securities are owned directly by Casdin Private Growth Equity Fund, L.P. (the "Equity Fund") and may be deemed to be indirectly beneficially owned by (i) Casdin, the investment adviser to the Equity Fund, and (ii) Eli Casdin, the managing member of Casdin.

Remarks:

Eli Casdin has been deputized to represent the Reporting Persons on the board of directors of the Issuer. By virtue of Mr. Casdin's representation, for purposes of Section 16 of the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons may be deemed directors by deputization of the Issuer. Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.

	Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member	11/12/2025
	/s/ Eli Casdin, Eli Casdin	11/12/2025
	Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member	11/12/2025
	Casdin Private Growth Equity Fund II, L.P., By: Casdin Private Growth Equity Fund II GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member	11/12/2025
	Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member	11/12/2025
	Casdin Private Growth Equity Fund GP II, LLC, By: /s/ Eli Casdin, Managing Member	11/12/2025
	Casdin Private Growth Equity Fund, L.P., By: Casdin Private Growth Equity Fund II GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member	11/12/2025
	Casdin Private Growth Equity Fund GP, LLC, By: /s/ Eli Casdin, Managing Member	11/12/2025
	** 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 did insiders report for Standard BioTools (LAB)?

Affiliates of Eli Casdin reported open‑market purchases totaling 1,175,000 shares across four dates in November 2025.

On which dates and how many LAB shares were bought?

11/07: 225,000; 11/10: 275,000; 11/11: 300,000; 11/12/2025: 375,000.

What prices were paid for the LAB share purchases?

Weighted average prices were $1.1234, $1.1706, $1.196, and $1.1889, with transaction ranges noted in the footnotes.

How many shares were beneficially owned after the transactions?

The Master Fund’s indirectly beneficially owned balance is listed as 62,050,000 shares following the reported transactions.

What other holdings were disclosed by LAB insiders in this filing?

2,901,062 shares directly by Eli Casdin; 13,939,637 shares indirectly by Casdin Private Growth Equity Fund II, L.P.; 2,744,219 shares indirectly by Casdin Private Growth Equity Fund, L.P.

Was the Form 4 filed by multiple reporting persons?

Yes. The form indicates it was filed by more than one reporting person.