---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-164529"
form_type: "8-K"
ticker: "ONTO"
cik: "0000704532"
company_name: "ONTO INNOVATION INC."
filed_at: "2026-04-21T23:59:59+00:00"
generated_at: "2026-05-15T05:13:12.197881+00:00"
event_type: "m_and_a"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Onto Innovation to acquire 27% stake in Rigaku for $710M; strategic partnership deepened

## Summary
- Purchase price ~$710M for 61.1M shares (27% of Rigaku) from Carlyle affiliate; expected close H2 2026.
- Acquisition to accelerate joint X-ray/OCD process control solutions; already selected by two key customers.
- Investment expected to be accretive as of Dec 31, 2026; Onto gets one board seat.
- $500M bridge loan commitment from Goldman Sachs to help finance the deal and related expenses.
- Market for CD-SAXS and metrology solutions estimated >$1B in five years per TechInsights.

## SEC filing metadata
- accession: 0001193125-26-164529
- form_type: 8-K
- ticker: ONTO
- cik: 0000704532
- company_name: ONTO INNOVATION INC.
- filed_at: 2026-04-21T23:59:59+00:00
- event_type: m_and_a
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 1.01, 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/704532/000119312526164529/0001193125-26-164529-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/704532/000119312526164529/d75499d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-164529
- JSON: https://secwatch.observer/filing/0001193125-26-164529.json
- Plain text: https://secwatch.observer/filing/0001193125-26-164529.txt

## Key facts
- Material Agreements
  ONTO INNOVATION INC. entered into Share Purchase Agreement with Atom Investments, L.P. valued at approximately $710 million (effective 2026-04-21).
  - Action: entry
  - Agreement: asset purchase
  - Counterparty: Atom Investments, L.P.
  - Value: approximately $710 million
  - Effective: 2026-04-21
  source text: On April 21, 2026 (Tokyo time), Onto Innovation Inc. (the “Company”) entered into a Share Purchase Agreement (the “Purchase Agreement”), with Atom Investments, L.P. (the “Seller”), an affiliate of The Carlyle Group, pursuant to which the Company agreed to acquire 61,123,436 shares (27% of the issued and outstanding shares) of the common stock of Rigaku Holdings Corporation (“Rigaku”), from the Seller for an aggregate purchase price of approximately $710 million
  evidence_url: https://www.sec.gov/Archives/edgar/data/704532/000119312526164529/0001193125-26-164529-index.htm

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