ARCH Venture funds add Lyell (LYEL) stake with 488,090-share buy

Rhea-AI Filing Summary

ARCH Venture funds increased their indirect stake in Lyell Immunopharma, Inc. by purchasing 488,090 shares of common stock in an open-market transaction on March 6, 2026, at $25.61 per share. The filing attributes ownership to ARCH Venture Fund IX-affiliated limited partnerships, with the general partner and managing directors disclaiming beneficial ownership beyond their pecuniary interests.

Insights

Equity analyst

ARCH Venture funds disclosed a sizable open-market purchase in Lyell shares.

The Form 4 shows ARCH Venture Fund IX-affiliated entities indirectly acquiring 488,090 shares of Lyell Immunopharma common stock at $25.61 per share in an open-market transaction on March 6, 2026. The reporting structure runs through multiple ARCH general-partner entities.

Footnotes clarify that the shares are directly held by ARCH limited partnerships, and the general partners and managing directors disclaim beneficial ownership except for any pecuniary interest. This means economic exposure sits primarily at the fund level, with governance influence mediated through those partnerships.

The disclosure updates Lyell’s ownership picture by documenting additional indirect holdings by a more-than-ten-percent owner group. Future company filings may further detail how these fund-level positions evolve over time and how overall ownership concentration among major holders changes.

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^*

ARCH Venture Partners IX, LLC

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Lyell Immunopharma, Inc. [ LYEL ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
03/06/2026

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	03/06/2026		P		488,090	A	$25.61	1,426,528	I	See footnote(1)
Common Stock								910,317	I	See footnote(2)
Common Stock								910,317	I	See footnote(3)

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^*

ARCH Venture Partners IX, LLC

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Partners IX, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Partners IX Overage, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Fund IX, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ARCH Venture Fund IX Overage, L.P.

(Last) (First) (Middle)

8755 W. HIGGINS ROAD, SUITE 1025

(Street)

CHICAGO IL 60631

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. These shares are directly held by ARCH Venture Fund XIII, L.P. ("ARCH XIII"). ARCH Venture Partners XIII, L.P. ("AVP XIII LP") is the general partner of ARCH XIII. ARCH Venture Partners XIII, LLC ("AVP XIII LLC") is the general partner of AVP XIII LP. Keith Crandell, Robert Nelsen, Kristina Burow, Paul Berns and Steven Gillis are members of the investment committee of AVP XIII LLC (the "AVP XIII LLC Committee Members"). Each of AVP XIII LP and AVP XIII LLC may be deemed to beneficially own the shares held by ARCH XIII, and each of the AVP XIII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XIII. Each of AVP XIII LP, AVP XIII LLC and the AVP XIII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any.

2. These shares are directly held by ARCH Venture Fund IX, L.P. ("ARCH IX"). ARCH Venture Partners IX, L.P. ("GPLP"), as the sole general partner of ARCH IX, may be deemed to beneficially own the shares held by ARCH IX. ARCH Venture Partners IX, LLC ("GPLLC"), as the sole general partner of GPLP, may be deemed to beneficially own the shares held by ARCH IX. As managing directors of GPLLC, each of Keith Crandell, Robert Nelsen and Clinton Bybee (the "ARCH Managing Directors"), may be deemed to beneficially own the shares held by ARCH IX. Each of GPLP, GPLLC and the ARCH Managing Directors disclaims beneficial ownership of the securities reported herein, except to the extent of their pecuniary interest therein, if any.

3. These shares are directly held by ARCH Venture Fund IX Overage, L.P. ("ARCH Overage"). ARCH Venture Partners IX Overage, L.P. ("Overage GPLP"), as the sole general partner of ARCH Overage, may be deemed to beneficially own the shares held by ARCH Overage. GPLLC, as the sole general partner of Overage GPLP, may be deemed to beneficially own the shares held by ARCH Overage. As managing directors of GPLLC, each of the ARCH Managing Directors may be deemed to beneficially own the shares held by ARCH Overage. Each of Overage GPLP, GPLLC and the ARCH Managing Directors disclaims beneficial ownership of the securities reported herein, except to the extent of their pecuniary interest therein, if any.

Remarks:

This Form 4 is one of two reports relating to the same transaction being filed jointly by ARCH Venture Partners XIII, LLC, ARCH Venture Partners XIII, L.P., ARCH Venture Fund XIII, L.P., Keith Crandell, Robert Nelsen, Kristina Burow, Steven Gillis, Paul Berns, Clinton Bybee, ARCH Venture Partners IX, LLC, ARCH Venture Partners IX, L.P., ARCH Venture Partners IX Overage, L.P., ARCH Venture Fund IX, L.P. and ARCH Venture Fund IX Overage, L.P.

	ARCH Venture Partners IX, LLC, By: /s/ Mark McDonnell, as Attorney-in-Fact for Robert Nelsen, Managing Director	03/09/2026
	ARCH Venture Partners IX, L.P., By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	ARCH Venture Partners IX Overage, L.P., By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	ARCH Venture Fund IX, L.P., By: ARCH Venture Partners IX, L.P., its General Partner, By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	ARCH Venture Fund IX Overage, L.P., By: ARCH Venture Partners IX Overage, L.P., its General Partner, By: ARCH Venture Partners IX, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	** Signature of Reporting Person	Date
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FAQ

What insider transaction did ARCH Venture funds report in Lyell Immunopharma (LYEL)?

ARCH Venture Fund IX-affiliated entities reported an indirect open-market purchase of 488,090 shares of Lyell Immunopharma common stock. The shares were bought at $25.61 each on March 6, 2026, increasing the funds’ economic exposure to Lyell through their limited partnership structures.

Who actually holds the Lyell (LYEL) shares reported in this ARCH Venture Form 4?

The shares are directly held by ARCH Venture Fund IX, L.P. and ARCH Venture Fund IX Overage, L.P., according to the footnotes. Related ARCH general-partner entities may be deemed beneficial owners, but they and their managing directors disclaim beneficial ownership beyond any pecuniary interest they hold.

How many Lyell Immunopharma (LYEL) shares did ARCH Venture funds buy and at what price?

ARCH Venture Fund IX-affiliated entities acquired 488,090 shares of Lyell Immunopharma common stock in an open-market transaction. The disclosed purchase price was $25.61 per share, as reported for the March 6, 2026 transaction in the Form 4 filing with the SEC.

Is the ARCH Venture Lyell (LYEL) stake held directly or indirectly by the reporting persons?

The Form 4 indicates the Lyell shares are held indirectly through ARCH limited partnerships, not directly by individuals. General-partner entities and managing directors are listed as potential beneficial owners, but they expressly disclaim beneficial ownership except to the extent of any pecuniary interest in the funds.

What does the beneficial ownership disclaimer mean in the ARCH Venture Lyell (LYEL) filing?

The disclaimer states that general-partner entities and managing directors do not claim full beneficial ownership of the Lyell shares. They may be deemed owners only to the extent of their economic, or pecuniary, interest in the ARCH funds that directly hold the shares, limiting personal ownership claims.

How does this ARCH Venture transaction affect large-holder status in Lyell Immunopharma (LYEL)?

ARCH Venture IX-related entities are identified as more-than-ten-percent owners of Lyell Immunopharma. The disclosed 488,090-share open-market purchase increases their fund-level position, updating the ownership profile among Lyell’s significant shareholders as reflected in Section 16 insider reporting requirements.