📜 What This Document Is 📃

This filing is not the main 8-K report itself, but rather a highly detailed Exhibit 2.1: Share Purchase Agreement. Think of this contract as the rulebook for a major corporate transaction. Instead of reporting results, this document outlines the specific, legally binding terms for one company to buy a substantial block of shares from another entity.

👉 What to expect: The details here are dense legal guarantees, defining who is selling (Atom Investment, L.P.) and who is buying (Onto Innovation Inc.), how much it will cost, and what conditions must be met to close the deal.

🏢 Onto Innovation Inc. Overview ✨

Before diving into the legal complexity, it’s helpful to know who Onto Innovation is. The company is a major player in the semiconductor manufacturing sector, specializing in what’s known as "process control."

👉 In simple terms: Onto Innovation helps chip makers solve their toughest problems—like ensuring perfect quality, detecting tiny flaws, and increasing performance—through an expanded suite of advanced technologies.

Onto is headquartered in Wilmington, Massachusetts, and provides services across the entire semiconductor value chain. Their offerings include un-patterned wafer quality checks, 3D metrology (measuring features from nanometer transistors to large interconnects), defect inspection, and factory analytics.

🔗 The Core Transaction Details 💰

This entire agreement hinges on a single transaction: the sale of shares. Atom Investment, L.P., is selling a block of stock belonging to a third entity, Rigaku Holdings Corporation. Onto Innovation is the buyer of these shares.

• Shares Involved: Atom Investment, L.P., owns 95,140,800 shares of Rigaku Holdings Corporation. Onto Innovation Inc. plans to purchase 61,123,436 shares (the "Shares").
• The Price: The purchase price is set at JPY 1,850 per share.
• The Goal: This agreement establishes the terms under which Onto Innovation will acquire this specific number of shares from the Seller.

📅 Closing Timeline and Mechanics 🗓️

The agreement lays out a precise timeline for the transaction to finalize. The Closing Date is scheduled for July 1, 2026. If certain pre-closing conditions are not met by that date, the closing will move to the fifth Business Day immediately following the initial date.

• The Process: At closing, Onto Innovation must pay the full Purchase Price to Atom Investment, L.P., via wire transfer. In exchange, Atom must apply for the transfer of the Shares into Onto Innovation’s account.
• Required Preparation: Both parties are required to do specific actions simultaneously to ensure the transaction completes smoothly, which is why the legal details are so robust.

🛡️ Guarantees from the Seller (Atom Investment) 📜

The Seller (Atom Investment, L.P.) provides extensive legal guarantees, known as representations and warranties, to protect the Buyer. These clauses assure Onto Innovation that everything about the shares and the Seller’s ability to transact is legitimate.

• Ownership: The Seller guarantees it is the sole beneficial and record owner of the Shares, free and clear of any major debts or claims (Liens).
• Legality: The Seller affirms that the transaction does not violate any laws or existing contracts, nor does it involve any undisclosed material information.
• Safety: Crucially, the Seller explicitly warrants that it is not connected to any organized crime group ("Anti-Social Forces").

✍️ Guarantees from the Buyer (Onto Innovation) 🛡️

The Buyer also makes several major commitments to protect the Seller. These guarantees confirm that Onto has the corporate power, ability, and financial health to complete the purchase.

• Financial Strength: Onto Innovation warrants that it has sufficient funds to cover the required payments (the "Required Amount"), supported by a Debt Commitment Letter. This signals strong financial backing.
• Authorization: Onto guarantees that the purchase is authorized by all necessary actions of the company.
• Market Understanding: Onto acknowledges that it is responsible for its own evaluation of the transaction and does not rely on any projections or forecasts provided by the Seller.

🌊 Dealing with Risks and Uncertainty ⚠️

Because this is such a large deal, the contract spends significant time defining "risk," or how unforeseen negative events could impact the deal.

• Material Adverse Effect (MAE): The agreement contains a complex definition of an MAE—an event that would severely damage the business or financial condition of the company. However, the contract lists exceptions, meaning general industry shifts, global political changes, or even natural disasters are typically not considered an MAE.
• Loss Limitation: The agreement also restricts liability, meaning neither party can be held responsible for certain types of damage, such as indirect, incidental, or special losses.

📞 Contacts and Next Steps 📍

While the exhibit does not list general corporate contact information, it does specify how and where the legal processes will take place.

• Closing Location: The purchase and sale will take place at Nagashima Ohno & Tsunematsu Tokyo Office.
• Legal Contact: All required notices must be delivered to a bank account designated by the Seller, and the transaction requires written notice of the intended shares and the Buyer Designee.

🧠 The Analogy

Buying a large block of shares through a complex legal agreement is like commissioning a custom, high-end car. You aren't just buying the car; you are signing a massive contract that covers everything: who built the engine (Seller's guarantees), that the chassis is sound (Onto's financing guarantees), that it will arrive on time (the Closing Date), and what happens if a major storm hits on the way (the MAE clause). Every article is a detailed promise to ensure the final product matches the initial vision.

🧩 Final Takeaway

This document is a highly formal, legal roadmap for Onto Innovation to acquire over 61 million shares of Rigaku Holdings Corporation. The transaction is structured to be legally airtight, placing significant guarantees on both the Seller's past performance and the Buyer's ability to close the purchase by July 1, 2026.