The owner of The New York Times, The Boston Globe, and other media properties was the S&P 500’s top gainer on talk it may be acquired. Mexican billionaire Carlos Slim owns about 7 percent of the Class A shares; warrants would give him control of 16 percent of the shares. “The rumor mill is being cranked up again saying Carlos Slim wants to buy the company,’’ said Edward Atorino, at Benchmark Co. “But it’s a complicated process . . . I never want to say never, but these rumors have come and gone before.’’ A spokesman said Slim doesn’t want control.