---
schema_version: "secwatch.filing_event.v1"
accession: "0001104659-26-001125"
form_type: "8-K"
ticker: null
cik: "0001442836"
company_name: "Mersana Therapeutics, Inc."
filed_at: "2026-01-06T23:59:59+00:00"
generated_at: "2026-05-16T11:31:49.970280+00:00"
event_type: "m_and_a"
sentiment: "neutral"
materiality_score: 0.95
calibrated_materiality_score: 0.95
confidence: "high"
source: SEC EDGAR
---

# Mersana acquired by Day One for $25.00/share plus CVR up to $30.25

## Summary
- Tender offer expired Jan 5, 2026; 60.57% of shares tendered; merger closed Jan 6, 2026.
- Consideration: $25.00 per share cash plus one non-tradeable CVR per share with potential milestone payments up to $30.25.
- CVR milestones include FDA approval for ACC-1 ($9.00), first patient dosed ($4.00), and net sales thresholds; total max $30.25 per CVR.
- All pre-merger directors resigned; Charles N. York II and Adam Dubow appointed directors; stock delisted from Nasdaq.

## SEC filing metadata
- accession: 0001104659-26-001125
- form_type: 8-K
- cik: 0001442836
- company_name: Mersana Therapeutics, Inc.
- filed_at: 2026-01-06T23:59:59+00:00
- event_type: m_and_a
- sentiment: neutral
- materiality_score: 0.95
- calibrated_materiality_score: 0.95
- confidence: high
- sec_items: 1.02, 2.01, 3.01, 3.03, 5.01, 5.02, 5.03, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1442836/000110465926001125/0001104659-26-001125-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1442836/000110465926001125/tm261736d24_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001104659-26-001125
- JSON: https://secwatch.observer/filing/0001104659-26-001125.json
- Plain text: https://secwatch.observer/filing/0001104659-26-001125.txt

## Source-grounded claims
- claim_id: 465d7bf82c0d5486ea07059bdb142e5e3ba95670
  claim: Mersana Therapeutics, Inc.: Certificate of incorporation amended and restated in its entirety effective as of the Effective Time pursuant to the Merger Agreement.
  evidence_excerpt: the certificate of incorporation of the Company was amended and restated in its entirety, effective as of the Effective Time
  evidence_url: https://www.sec.gov/Archives/edgar/data/1442836/000110465926001125/0001104659-26-001125-index.htm
- claim_id: 6ddff0aa5c4904ab7cd070949d70315abfeff80a
  claim: Mersana Therapeutics, Inc.: Bylaws amended and restated in their entirety effective as of the Effective Time pursuant to the Merger Agreement.
  evidence_excerpt: the bylaws of the Company were amended and restated in their entirety, effective as of the Effective Time
  evidence_url: https://www.sec.gov/Archives/edgar/data/1442836/000110465926001125/0001104659-26-001125-index.htm
- claim_id: 98d53bcea63be5f5d4b7c695b6a7866ebe4036ba
  claim: Mersana Therapeutics, Inc. underwent a change of control involving Day One Biopharmaceuticals, Inc. for $25.00 per Share in cash plus one non-tradeable contingent value right per share (closed 2026-01-06).
  evidence_excerpt: offer (the “Offer”) to acquire all of the issued and outstanding shares (the “Shares”) of common stock, par value $0.0001 per share, of the Company (the “Common Stock”), for (i) $25.00 per Share, net to the stockholder in cash, without interest and less any applicable tax withholding(the “Upfront Cash Consideration”), plus (ii) one non-tradeable contingent value
  evidence_url: https://www.sec.gov/Archives/edgar/data/1442836/000110465926001125/0001104659-26-001125-index.htm

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