Nvidia shares plunged on Thursday as Wall Street reacted to the resignation of chief executive Jensen Huang, dragging down the wider US stock market and other artificial intelligence stocks.

The shares fell as much as 14% when trading opened, before steadying to around 7% lower at about $161. The drop wiped billions of dollars off the value of the world’s most important AI chipmaker.

The S&P 500 fell 0.6% and the Nasdaq composite dropped 0.9% in morning trading, while the Dow Jones Industrial Average was almost flat. Nvidia alone accounts for about 6% of the S&P 500.

01. Seven brokerages downgrade Nvidia

Seven brokerages cut their ratings on Nvidia between Wednesday and Thursday morning, NDTV Profit reported. Baird, Oppenheimer, Bernstein, Evercore ISI, William Blair, KeyBanc and Melius Research all removed the stock from their buy-equivalent recommendations.

Bernstein analyst Stacy Rasgon cut his rating to market perform and slashed his price target from $400 to $200, while calling the shares “almost absurdly cheap” at current levels.

Other firms, including Cantor Fitzgerald, BMO Capital Markets, Citi, Stifel and RBC, kept bullish ratings but sharply lowered their price targets.

02. Rivals gain as investors look elsewhere

Some of Nvidia’s rivals rose as investors bet they could benefit. Shares in AMD, Nvidia’s closest rival, were up more than 7% at Wednesday’s close and rose again on Thursday, while Broadcom gained about 4%.

Nvidia’s shares had already fallen 27% since its board announced an investigation into Huang, and are now about 40% below last year’s record highs.

Morningstar kept its “wide economic moat” rating for Nvidia and its $310 fair value estimate, saying it would be hard for rivals to challenge the company’s position.

03. What happens next

Huang resigned as president, chief executive and board member with immediate effect on Thursday. Chief financial officer Colette Kress has taken over as interim chief executive, and the board has begun searching for a permanent replacement.

Nvidia is due to report its third-quarter results on Tuesday, November 17. Investors will be watching whether the company keeps its strategy of spending heavily to support the AI industry, and who the board chooses as its next chief executive.

Earlier: Jensen Huang resigns as Nvidia CEO; Colette Kress takes over as interim chief