A Form 4 filed on August 17, 2026 discloses that John Tseng-Chung Lee, President and Chief Executive Officer of MKS Inc. (NASDAQ:MKSI), sold 10,000 shares of common stock on August 14, 2026 pursuant to a pre-established Rule 10b5-1 trading plan.

Key Highlights

  • Transaction date: 10,000 shares of MKS Inc. common stock were sold on August 14, 2026.
  • Sale price: Shares were disposed of at $302.01 each, according to the filing.
  • Remaining ownership: Following the transaction, the reporting person directly beneficially owns 134,776.2667 shares.
  • 10b5-1 plan: The sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 20, 2026.
  • Reporting person: John Tseng-Chung Lee is identified as both a Director and the President and CEO of MKS Inc.

MKS Inc. CEO Share Sale Details and Plan Background

According to the Form 4 filed with the U.S. Securities and Exchange Commission, John Tseng-Chung Lee, who serves as President, Chief Executive Officer, and Director of MKS Inc. (NASDAQ:MKSI), disposed of 10,000 shares of the company's common stock on August 14, 2026. The shares were sold at a price of $302.01 per share, and the transaction is classified with a disposition code of "S" in Table I of the filing.

The filing states that the transaction was made directly and was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 20, 2026. The filing also notes, via the checked box on the form, that the transaction was made pursuant to a contract, instruction, or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). Following the reported sale, Lee's direct beneficial ownership of MKS Inc. common stock stands at 134,776.2667 shares, as reported in the filing.

The Form 4 was signed by M. Kathryn Rickards as attorney-in-fact and was filed on August 17, 2026. No derivative securities transactions were reported in Table II of the filing. The issuer address listed for the reporting person is 2 Tech Drive, Andover, Massachusetts 01810.

What Was Disclosed

The filing reports a single open-market sale of 10,000 shares of MKS Inc. common stock by the company's President and CEO on August 14, 2026, at $302.01 per share, conducted under a pre-adopted Rule 10b5-1 plan, leaving a direct beneficial ownership of 134,776.2667 shares.