Shift4 Payments shares gained as much as 5% in U.S. pre-market trading on Tuesday after Chief Executive Officer Jared Isaacman disclosed that he bought about 195,000 of the company’s shares for roughly $16.3 million. The purchase, dated 8 Aug. according to a regulatory filing, came after the payments processor’s stock had fallen about 20% in recent weeks. Isaacman’s latest acquisition adds to a history of insider buying that investors often view as a signal of confidence in the company’s prospects.