On Jan. 28, 2026, Dr. Constantin Ionel Stefan, CTO of Amprius Technologies (NYSE:AMPX), sold 39,690 shares of common stock, totaling $476,351, in an open-market transaction as reported in an SEC Form 4 filing. Post-transaction, he held 748,696 shares valued at $9.0 million.

The transaction was a derivative event involving stock options exercise, indicating a 5.03% reduction in direct holdings for Dr. Stefan. This reduction suggests a significant decrease in available shares, with direct holdings now less than half of the recent period’s start.

Executed under a Rule 10b5-1 trading plan, the sale aligns with Amprius’s 358.75% one-year stock price appreciation as of Jan. 28, 2026. Dr. Stefan’s transaction size reflects the remaining capacity rather than a change in selling pattern.

Amprius Technologies, with a $1.60 billion market cap, specializes in silicon nanowire anode lithium-ion batteries for aerospace, defense, and electric vehicles. The company reported $57.81 million in revenue (TTM) and a net income of ($31.78 million) as of Jan. 28, 2026.

Dr. Stefan’s sale of Amprius stock, part of a trading plan, doesn’t signal concern. Despite selling nearly 40,000 shares, he retains almost 750,000, indicating a long-term commitment. The stock’s growth reflects demand for its batteries, particularly in aerospace and defense sectors.

Investors may want to consider Amprius stock carefully. While the company shows strong revenue growth and a rising stock price, with a 358.75% one-year increase, its high price-to-sales ratio suggests an expensive valuation. Waiting for a potential price dip may be wise.

The Motley Fool Stock Advisor team did not include Amprius Technologies among their top 10 stock picks. Investors should weigh the company’s growth potential and valuation carefully before making investment decisions. The Stock Advisor’s total average return is 914%, outperforming the S&P 500.

Read more at Yahoo Finance: Is Amprius Stock a Buy or Sell After Its Chief Technology Officer Dumped Nearly 40,000 Shares?