---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-341337"
form_type: "8-K"
ticker: "ONTO"
cik: "0000704532"
company_name: "ONTO INNOVATION INC."
filed_at: "2026-08-10T12:16:49+00:00"
generated_at: "2026-08-10T12:20:10.989915+00:00"
event_type: "m_and_a"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Onto Innovation closes $720M purchase of 27% stake in Rigaku Holdings

## Summary
- Completed purchase of 61,123,436 Rigaku shares (27% of outstanding) from Atom Investment, a Carlyle affiliate, for ~$720M (¥113.08B).
- Investment deepens strategic collaboration on X-ray process control for semiconductor manufacturing; first announced April 2026.
- Onto will account for investment under fair value option, not consolidate Rigaku; will nominate a director to Rigaku's board.
- CEO Mike Plisinski says investment accelerates innovation and enhances holistic process control solutions for next-gen chips.

## SEC filing metadata
- accession: 0001193125-26-341337
- form_type: 8-K
- ticker: ONTO
- cik: 0000704532
- company_name: ONTO INNOVATION INC.
- filed_at: 2026-08-10T12:16:49+00:00
- event_type: m_and_a
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 2.01, 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/704532/000119312526341337/0001193125-26-341337-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/704532/000119312526341337/d125405d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-341337
- JSON: https://secwatch.observer/filing/0001193125-26-341337.json
- Plain text: https://secwatch.observer/filing/0001193125-26-341337.txt

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