Wall Street's main indexes posted record-high closes Thursday, a day after the U.S. Federal Reserve delivered a quarter-point interest rate cut, while chipmaker Intel rose after Nvidia decided to build a stake in the company. Intel was on track for its biggest daily gain since October 1987 after Nvidia said it would invest $5 billion in the struggling U.S. chipmaker. Peer Advanced Micro Devices slipped. Nvidia rose, recovering losses from Wednesday when a report said Chinese tech firms might stop buying its chips. The moves boosted a broader semiconductor index, and also lifted the tech-heavy Nasdaq and the S&P 500…