Pappis Charles C 4

What Happened
Charles C. Pappis, a director of ACM Research, exercised 5,000 fully vested stock options on April 17, 2026 at an exercise price of $29.18 per share (cost $145,900) and then sold the 5,000 resulting Class A shares in the open market at $52.00 per share for $260,000. The transactions effectively converted options into common stock and immediately disposed of those shares.

Key Details

• Transaction date: April 17, 2026.
• Exercise: 5,000 shares @ $29.18 = $145,900 (reported as an option exercise, code M).
• Sale: 5,000 shares @ $52.00 = $260,000 (open-market sale, code S).
• Derivative disposition: 5,000 options reported as disposed at $0 reflecting conversion/exercise of the option instrument.
• Sale executed pursuant to a Rule 10b5-1 trading plan adopted Nov 20, 2025.
• The option was fully vested and exercisable at time of exercise.
• Net cash difference from these transactions (sale proceeds minus exercise cost): $114,100 (before taxes/fees).
• Shares owned after the transaction are not specified in the provided excerpt.
• Filing date: April 21, 2026 — filed within the Form 4 two-business-day window (timely).

Context
This was an option exercise followed by an immediate sale of the exercised shares (common practice to monetize vested options). The 10b5-1 plan indicates the sale was pre-arranged and not an ad-hoc disposition. These filings are factual disclosures of transactions and do not, by themselves, indicate the insider’s view of the company's prospects.