Nvidia’s shares sank Thursday, sending tremors through global markets, as the company’s chief executive, Jensen Huang, stepped down from his role.

Shares in Nvidia dropped more than 4 percent by the time markets closed for trading on Thursday, wiping out nearly $1 trillion from the company’s market value this month alone. The stock fell by as much as 14 percent Thursday morning but pared most of those losses as investors’ fears about the company’s future without Mr. Huang eased.

Nvidia has emerged as central to the A.I. economy because its chips — or graphic processing units — help train and power models across the industry. It has also become a central bank of sorts for several A.I. companies, because its finances are…