---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-129448"
form_type: "8-K"
ticker: "LYEL"
cik: "0001806952"
company_name: "Lyell Immunopharma, Inc."
filed_at: "2025-05-28T23:59:59+00:00"
generated_at: "2026-05-20T08:31:17.769981+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.55
calibrated_materiality_score: 0.55
confidence: "high"
source: SEC EDGAR
---

# Lyell Immunopharma announces 1-for-20 reverse stock split effective May 30, 2025

## Summary
- Reverse split at 1-for-20 ratio; effective 5:00 p.m. ET on May 30, 2025.
- Common stock begins split-adjusted trading on Nasdaq June 2, 2025.
- Proportionate adjustments to stock options, RSUs, and shares reserved under equity plans.
- Pre-split shares outstanding: ~296.2M; post-split: ~14.8M (subject to fractional cash-out).
- New CUSIP number: 55083R203; no change in par value or proportional ownership.

## SEC filing metadata
- accession: 0001193125-25-129448
- form_type: 8-K
- ticker: LYEL
- cik: 0001806952
- company_name: Lyell Immunopharma, Inc.
- filed_at: 2025-05-28T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.55
- calibrated_materiality_score: 0.55
- confidence: high
- sec_items: 3.03, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1806952/000119312525129448/0001193125-25-129448-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1806952/000119312525129448/d944707d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-129448
- JSON: https://secwatch.observer/filing/0001193125-25-129448.json
- Plain text: https://secwatch.observer/filing/0001193125-25-129448.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.