Jarrad Mattieu Aguirre - 10 Sep 2026 Form 4 Insider Report for Lyell Immunopharma, Inc. (LYEL)

Reporting relationship: Chief Medical Officer
Issuer ticker: LYEL
Reported as of: 10 Sep 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 10 Sep 2026, 19:31:56 UTC
Prior SEC filing: 10 Sep 2026
Source filing: View source filing
Reporting owner signature: /s/ Mark Meltz, Attorney-in-Fact

Key filing fact

Jarrad Mattieu Aguirre filed Form 4 for Lyell Immunopharma, Inc. (LYEL) on 10 Sep 2026.

Key facts

This page summarizes Jarrad Mattieu Aguirre's Form 4 filing for Lyell Immunopharma, Inc. (LYEL).
1 reported transaction and 1 derivative row are listed below.
Accepted by SEC: 10 Sep 2026, 19:31.

Change

Previous filing in this sequence was filed on 10 Sep 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002150331 Primary reporting owner

Aguirre Jarrad Mattieu

Relationship: Chief Medical Officer
Address: C/O LYELL IMMUNOPHARMA, INC., 201 HASKINS WAY, SOUTH SAN FRANCISCO
Signature: /s/ Mark Meltz, Attorney-in-Fact
Signature date: 10 Sep 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

LYEL holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 20,279
Date: 10 Sep 2026
Ownership: Direct
Footnotes: F1

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

LYEL transaction Derivative

Option (right to buy)

Award

Transaction value
Shares: +47,500
Change %
Price: $0.000000^*
Shares after: 47,500
Date: 10 Sep 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 47,500
Exercise price: $12.20
Footnotes: F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 2 footnotes

Footnote F1

Includes 14,451 restricted stock units ("RSUs") under the Issuer's 2021 Equity Incentive Plan that are subject to time-based vesting and will be settled in common stock subject to vesting as follows: the RSUs vest quarterly over the thirty month period following July 9, 2026; in each case, subject to the reporting person providing service through the applicable vesting date.

Footnote F2

12.5% of the option shares will vest on February 28, 2027, with the remaining option shares to vest in equal monthly installments over the following 42 months, subject to the reporting person providing service through the applicable vesting date.