US stocks rose Monday after a sizable regional bank merger spurred enthusiasm a bigger M&A wave is on the way and as AMD shares surged on a partnership with OpenAI. The market continued to grind higher even as a government shutdown dragged on into a second week.

The S&P 500 climbed 0.3%, while the Nasdaq Composite advanced 0.6%. The Dow Jones Industrial Average gained 55 points, or 0.1%.

The S&P 500 and Nasdaq Composite are coming off their fourth weekly advance in five weeks, rising 1.1% and 1.3%, respectively. The Dow rose for the third time in four weeks, advancing 1.1%.

AMD shares jumped 38% in early trading after reaching a deal with Sam Altman's AI leader that could ultimately end up giving the ChatGPT company a 10% stake in the chipmaker via a warrant with different tranches. AMD will use certain graphics processing units rolled out over multiple years. Nvidia, AMD's main competitor in graphics processors, came under pressure in the premarket following that announcement.

Comerica shares rallied 17% after Fifth Third Bancorp reached a deal to buy the fellow regional bank for $10.9 billion in an all-stock transaction. The merger will form the ninth-largest U.S. bank by assets. The SPDR S&P Regional Banking ETF jumped 1% in early trading on expectations more deals were ahead in the space. Overall M&A has been picking up, adding to the animal spirits seen in the stock market this year.