Form 4: Casdin Increases LAB Position by 500,000 Shares; Disposal of 2.9M by Eli Casdin

Rhea-AI Filing Summary

Casdin-related entities reported multiple transactions in Standard BioTools, Inc. (LAB). On 09/03/2025 and 09/04/2025, Casdin Partners Master Fund, L.P. purchased 250,000 shares each day at weighted-average prices of $1.2656 and $1.2774, respectively, increasing beneficial holdings to 60,525,000 and 60,775,000 shares as reported. Eli Casdin directly disposed of 2,901,062 shares. The filing lists additional direct holdings: Casdin Private Growth Equity Fund II, L.P. holds 13,939,637 shares and Casdin Private Growth Equity Fund, L.P. holds 2,744,219 shares. Footnotes explain weighted-average price ranges and indirect ownership through adviser and general partner relationships. The reporting persons disclaim beneficial ownership except to the extent of pecuniary interest.

Positive

• Master Fund increased holdings with two purchases totaling 500,000 shares at weighted-average prices of $1.2656 and $1.2774
• Clear disclosure of indirect ownership and price ranges via footnotes provides transparency for investors and the issuer

Negative

• Eli Casdin directly disposed of 2,901,062 shares, reducing his direct holdings
• Large related-party holdings concentrated across multiple Casdin entities may complicate assessment of beneficial ownership interests

Insights

Securities Analyst

TL;DR: Casdin entities modestly increased position in LAB via two small open-market purchases; an individual disposal of ~2.9M shares was also reported.

The report shows two purchases totaling 500,000 shares by the Master Fund across 09/03/2025 and 09/04/2025 at weighted-average prices of $1.2656 and $1.2774. The Form 4 also records a direct disposition of 2,901,062 shares by Eli Casdin and substantial direct holdings by affiliated private funds. Footnotes clarify ownership chains and price ranges. From a reporting perspective, these transactions update insider holdings and the relationships between the funds, adviser, GP and Eli Casdin.

Corporate Governance Expert

TL;DR: Multiple related reporting persons were deputized on the board and jointly filed Form 4, clarifying indirect ownership links.

The filing documents that Eli Casdin was deputized to represent the reporting persons on the issuer's board and that several Casdin entities may be deemed directors by deputization. The disclosure includes standard disclaimers of beneficial ownership and explains indirect ownership attribution through the adviser and general partner structures. The filing is procedural and informative regarding governance and Section 16 reporting obligations.

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)
09/03/2025

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	09/03/2025		P		250,000	A	$1.2656(1)	60,525,000	I	See footnote(2)
Common Stock, $0.001 par value per share	09/04/2025		P		250,000	A	$1.2774(3)	60,775,000	I	See footnote(2)
Common Stock, $0.001 par value per share								2,901,062	D(4)
Common Stock, $0.001 par value per share								13,939,637	I	See footnote(5)
Common Stock, $0.001 par value per share								2,744,219	I	See footnote(6)

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 $1.2414 to $1.2765. The Reporting Persons undertakes 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 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.

3. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.2621 to $1.2930. The Reporting Persons undertakes 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 Eli Casdin.

5. 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.

6. 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	09/05/2025
	Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member	09/05/2025
	Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member	09/05/2025
	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	09/05/2025
	Casdin Private Growth Equity Fund GP II, LLC, By: /s/ Eli Casdin, Managing Member	09/05/2025
	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	09/05/2025
	Casdin Private Growth Equity Fund GP, LLC, By: /s/ Eli Casdin, Managing Member	09/05/2025
	/s/ Eli Casdin, Eli Casdin	09/05/2025
	** 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 transactions did Casdin report on the Form 4 for LAB?

Answer: Purchases of 250,000 shares on 09/03/2025 at a weighted-average price of $1.2656 and 250,000 shares on 09/04/2025 at $1.2774, plus a direct disposition of 2,901,062 shares by Eli Casdin.

How many LAB shares do Casdin entities report beneficially owning after the purchases?

Answer: The filing reports beneficial ownership amounts of 60,525,000 and 60,775,000 shares corresponding to the reported purchase lines for the Master Fund.

Which Casdin funds hold additional LAB shares directly?

Answer: Casdin Private Growth Equity Fund II, L.P. directly owns 13,939,637 shares and Casdin Private Growth Equity Fund, L.P. directly owns 2,744,219 shares as reported.

What do the footnotes on price ranges mean?

Answer: Footnotes state the reported prices are weighted averages from multiple purchases within specified ranges and the reporting persons will provide per-transaction details on request.

Does the filing indicate any change in board representation?

Answer: The filing states Eli Casdin was deputized to represent the reporting persons on the issuer's board, which affects Section 16 attribution.