ARCH Venture Fund XIII boosts Lyell (LYEL) stake with 488K-share purchase

Rhea-AI Filing Summary

Lyell Immunopharma, Inc. reported an insider purchase by ARCH Venture Fund XIII, L.P. On March 6, 2026, ARCH Venture Fund XIII, L.P. made an open-market purchase of 488,090 shares of Lyell common stock at $25.61 per share, held indirectly through ARCH-related entities.

Following this transaction, ARCH Venture Fund XIII, L.P. held 1,426,528 Lyell shares. The filing also lists indirect holdings of 910,317 shares each for other ARCH-managed funds. General partners and investment committee members may be deemed beneficial owners but disclaim beneficial ownership except to the extent of any pecuniary interest.

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
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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 Fund XIII, L.P.

(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 Fund XIII, 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 XIII, 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 XIII, 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^*

CRANDELL KEITH

(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^*

NELSEN ROBERT

(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^*

Burow Kristina

(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^*

GILLIS STEVEN

(Last) (First) (Middle)

8755 WEST 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^*

BERNS PAUL L

(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^*

BYBEE CLINTON

(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 XIII, LLC, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	ARCH Venture Partners XIII, L.P., By: ARCH Venture Partners XIII, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	ARCH Venture Fund XIII, L.P., By: ARCH Venture Partners XIII, L.P., its General Partner, By: ARCH Venture Partners XIII, LLC, its General Partner, By: /s/ Mark McDonnell, as Attorney-in-Fact for Keith Crandell, Managing Director	03/09/2026
	Keith Crandell, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	03/09/2026
	Robert Nelsen, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	03/09/2026
	Kristina Burow, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	03/09/2026
	Steven Gillis, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	03/09/2026
	Paul Berns, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	03/09/2026
	Clinton Bybee, Managing Director, By: /s/ Mark McDonnell, as Attorney-in-Fact	03/09/2026
	** Signature of Reporting Person	Date
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FAQ

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

ARCH Venture Fund XIII, L.P. reported an open-market purchase of 488,090 Lyell Immunopharma common shares on March 6, 2026. The shares were bought at $25.61 per share and are held indirectly through ARCH-related investment entities as disclosed in the Form 4.

How many Lyell (LYEL) shares does ARCH Venture Fund XIII hold after this Form 4 transaction?

After the reported transaction, ARCH Venture Fund XIII, L.P. held 1,426,528 Lyell common shares. This figure reflects the total indirect position for that fund following the 488,090-share open-market purchase disclosed for the transaction date of March 6, 2026.

What price did ARCH Venture Fund XIII pay for Lyell Immunopharma (LYEL) shares?

ARCH Venture Fund XIII, L.P. paid $25.61 per share for Lyell Immunopharma common stock. The Form 4 shows this price for the 488,090 shares acquired in an open-market purchase on March 6, 2026, indicating a sizable indirect investment through ARCH-related entities.

Which ARCH entities are associated with the Lyell (LYEL) insider holdings reported?

The holdings involve ARCH Venture Fund XIII, L.P. and related entities, including ARCH Venture Partners XIII, L.P. and ARCH Venture Partners XIII, LLC. Additional shares are directly held by ARCH Venture Fund IX and ARCH Venture Fund IX Overage, with layered general-partner structures described in the footnotes.

Do ARCH partners personally own the Lyell Immunopharma (LYEL) shares reported?

ARCH’s general partners and investment committee members may be deemed beneficial owners under securities rules but disclaim beneficial ownership of the reported Lyell shares except to the extent of their pecuniary interest. The shares are directly held by ARCH funds rather than by the individuals personally.

What other Lyell (LYEL) share positions are disclosed for ARCH-related funds?

The Form 4 also discloses indirect holdings of 910,317 Lyell common shares for each of two additional ARCH-managed funds. These positions are held through ARCH Venture Fund IX and ARCH Venture Fund IX Overage structures, with layered general partners and managing directors outlined in the footnotes.