[Form 4] STANDARD BIOTOOLS INC. Insider Trading Activity

Rhea-AI Filing Summary

Standard BioTools Inc. (LAB) large shareholder and director-affiliated entities managed by Eli Casdin reported open-market purchases of common stock. On 11/18/2025, they bought 275,000 shares at a weighted average price of $1.2342, followed by 350,000 shares at $1.2826 on 11/19/2025 and 450,000 shares at $1.3028 on 11/20/2025.

After these transactions, one indirect holding line shows 64,050,000 shares of LAB common stock, with other lines reporting 2,901,062 shares directly and additional indirect positions of 13,939,637 and 2,744,219 shares. The filing explains that various Casdin funds hold these positions and that Eli Casdin and related entities may be deemed to beneficially own the securities through their advisory and general partner roles, while each reports ownership only to the extent of its economic interest.

Insights

Equity Analyst

Large insider purchases by an existing 10% owner/director increase indirect holdings and signal stronger economic exposure to the issuer.

This Form 4 reports open-market purchases of **STANDARD BIOTOOLS INC.** common stock by entities affiliated with **Eli Casdin** over three days, as a group already identified as a director and 10% owner. The Casdin Partners Master Fund bought **275,000**, **350,000**, and **450,000** shares on 11/18/2025, 11/19/2025, and 11/20/2025 at weighted average prices of $1.2342, $1.2826, and $1.3028. After these buys, one indirect position shown in Table I stands at **64,050,000** shares, alongside additional direct and indirect holdings through other Casdin-managed funds.

The filing explains that each daily price is an average of multiple trades within narrow ranges, with a commitment to provide detailed breakdowns on request. Ownership is spread across several vehicles (Master Fund, Growth Equity Fund and Fund II, related GPs, and **Casdin Capital, LLC**), all of which may be deemed to share beneficial ownership, while each party disclaims ownership beyond its economic interest. No derivative securities are reported in Table II, so the changes here reflect straightforward cash equity accumulation rather than option or warrant activity.

Eli Casdin is described as deputized to represent these entities on the issuer’s board, so these purchases link board-level representation with larger economic stakes. Key items to watch over the coming months are any follow-on Form 4 filings that change these share counts, and any future disclosures that clarify how this concentrated, board-connected ownership interacts with governance or corporate actions. The most concrete near-term reference point is the cluster of purchases completed by 11/20/2025 at the disclosed trading ranges.

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)
11/18/2025

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	11/18/2025		P		275,000	A	$1.2342(1)	63,250,000	I	See footnote(4)
Common Stock, $0.001 par value per share	11/19/2025		P		350,000	A	$1.2826(2)	63,600,000	I	See footnote(4)
Common Stock, $0.001 par value per share	11/20/2025		P		450,000	A	$1.3028(3)	64,050,000	I	See footnote(4)
Common Stock, $0.001 par value per share								2,901,062	D(5)
Common Stock, $0.001 par value per share								13,939,637	I	See footnote(6)
Common Stock, $0.001 par value per share								2,744,219	I	See footnote(7)

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 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 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, 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 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)

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)

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 $1.2247 to $1.2421. 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 $1.2758 to $1.2870. 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 $1.2788 to $1.3500 . 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 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.

5. The securities are owned directly by Eli Casdin.

6. 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.

7. 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	11/20/2025
	Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member	11/20/2025
	Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member	11/20/2025
	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	11/20/2025
	Casdin Private Growth Equity Fund GP II, LLC, By: /s/ Eli Casdin, Managing Member	11/20/2025
	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	11/20/2025
	Casdin Private Growth Equity Fund GP, LLC, By: /s/ Eli Casdin, Managing Member	11/20/2025
	/s/ Eli Casdin, Eli Casdin	11/20/2025
	** 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 Casdin-related entities report in this Form 4 for Standard BioTools (LAB)?

They reported open-market purchases of LAB common stock on three days in November 2025, increasing already large beneficial holdings in the company.

How many Standard BioTools (LAB) shares were purchased by Casdin-affiliated entities?

They bought 275,000 shares on 11/18/2025, 350,000 shares on 11/19/2025, and 450,000 shares on 11/20/2025, all reported as acquisitions (A).

What prices were paid for the Standard BioTools (LAB) shares in these Form 4 transactions?

The weighted average prices were $1.2342, $1.2826, and $1.3028 per share on the three respective trading dates, each based on multiple trades within stated price ranges.

How many Standard BioTools (LAB) shares are shown as indirectly held after the reported trades?

One indirect holding line shows 64,050,000 LAB common shares beneficially owned following the reported transactions.

Who is Eli Casdin in relation to Standard BioTools (LAB)?

Eli Casdin has been deputized to represent the Casdin reporting entities on Standard BioTools’ board, and for Section 16 purposes the reporting entities may be deemed directors by deputization.

Which entities hold the Standard BioTools (LAB) shares reported in this Form 4?

Holdings are reported for Casdin Partners Master Fund, L.P., Casdin Private Growth Equity Fund II, L.P., Casdin Private Growth Equity Fund, L.P., and Eli Casdin directly, with Casdin Capital LLC and general partner entities as indirect beneficial owners.

Do the Casdin reporting persons claim full beneficial ownership of all reported LAB shares?

Each reporting person disclaims beneficial ownership except to the extent of its pecuniary interest, and states that the report is not an admission of beneficial ownership for any other purpose.