Stock indexes closed mostly lower Tuesday as the market delivered a downbeat finish on the final day of another milestone-shattering year on Wall Street. The S&P 500 gave up an early gain to finish down 0.

The market outlook for 2025 sees U.S. GDP growing at a healthy rate, the stock market gains diversifying beyond the Magnificent Seven—with health care a likely winner—and an evolution in the AI sector that powered virtually all of last year’s rally.

Wall Street lost ground on Tuesday as investors closed the book on a remarkable year for equities, during which the U.S. stock market was powered to record highs by the twin engines of the artificial-intelligence boom and the U.