NEW YORK: Oil prices sank again Tuesday and dropped below $80 per barrel for the first time since early March, while U.S. stocks drifted near their all-time highs in mixed trading. The S&P 500 slipped 0.6% and pulled 1.3% below its record set earlier this month. The market was nearly evenly split between stocks rising and falling, and the Dow Jones Industrial Average added 328 points, or 0.6%, to set a record for the second straight day. But drops for some influential tech stocks pulled the Nasdaq composite down 1.2%. Stocks that had benefited from the boom in artificial-intelligence technology...