Shares of Plug Power (PLUG) tumbled 5.74% in after-hours trading on Monday, despite positive news about a major stock purchase by the company's CFO and a new international deal. The decline comes after the stock had surged over 25% during the regular trading session.

Earlier in the day, Plug Power announced that CFO Paul Middleton had purchased 650,000 shares of the company's common stock at an average price of $1.03 per share. This significant insider buying was seen as a vote of confidence in the company's long-term strategy and financial trajectory. Additionally, Plug Power revealed an expansion of its partnership with Allied Green Ammonia, including a new 2-gigawatt electrolyzer project in Uzbekistan as part of a $5.5 billion sustainable fuels initiative.

However, the after-hours sell-off suggests that investors may be taking profits after the day's substantial gains or remain cautious about the company's financial health. Plug Power has been facing challenges, including slowing revenue growth and significant losses. The company is currently seeking shareholder approval to sell more shares to raise cash and avoid a potential reverse stock split. Despite the positive developments, concerns about the company's cash burn and uncertain path to profitability appear to be weighing on investor sentiment in the short term.