AMD was the best-performing stock in the S&P 500 Wednesday. CFOTO / Contributor / Getty Images Close Key Takeaways A semiconductor stock powered higher after the company highlighted strong demand trends and provided an upbeat sales forecast at its first-ever analyst day. Meanwhile, shares of an artificial intelligence software firm gave back some of their recent gains. Major U.S. equities indexes ended with mixed results Wednesday as the House of Representatives prepared for a vote that could bring an end t ...