Investing.com -- Planet Fitness Inc (NYSE: PLNT) shares gained ground on Monday as positive momentum built from significant insider buying disclosures. The stock climbed 1.7% during the trading session as investors reacted to recent regulatory filings detailing executive purchases.

Chief Executive Officer Colleen Keating expanded her stake in the fitness company last week with an open-market purchase. According to a Form 4 filed with the Securities and Exchange Commission, Keating acquired 5,000 shares of Class A common stock on May 12, 2026, at a price of $49.54 per share.

The transaction was valued at approximately $250,000 and increases her direct holdings significantly. Following this purchase, the chief executive now beneficially owns a total of 141,511 shares in the company.

Keating was not the only corporate insider to boost her equity position in the firm earlier this month. Board member Frances Rathke also acquired 5,000 shares in the open market on May 8, 2026.

Rathke executed her transaction through a revocable trust account at a share price of $46.21. This strategic acquisition brings her total combined direct and indirect ownership to 33,746 shares.

Investors reacted well to the insider buys, which signaled executive confidence and potential undervaluation to the broader market. The coordinated accumulation by top leadership helped drive positive sentiment and upward momentum for the stock over the session.