Stéphane Bancel, chief executive officer of Moderna, has sold roughly $40 million worth of stock in the company since the beginning of this year.

Stephane Bancel, chief executive officer of Moderna Therapeutics Inc., stands for a photograph at the company’s office in Cambridge, Massachusetts, U.S., on Tuesday, Nov. 14, 2017. Moderna this week started testing a personalized treatment that teaches the body how to fight cancer. Photographer: Adam Glanzman/Bloomberg via Getty Images