Microsoft Corp. is resuming its pursuit of Yahoo Inc. in an attempt to better compete with Web search and advertising leader Google Inc., published reports said Friday. Yahoo shares surged more than 17 percent in midday trading. The New York Post reported Friday that Microsoft has asked Yahoo to enter formal negotiations for an acquisition that could be worth $50 billion. Yahoo's market capitalization was about $38 billion on Thursday. Microsoft, based in Redmond, Wash., had no immediate comment on the report, spokesman Lou Gellos said Friday. Yahoo spokeswoman Joanna Stevens also declined comment, saying "We don't discuss rumors and speculation." The Wall Street Journal said executives of the two companies are looking at a merger or some other kind of matchup and said the talks appear to be early-stage discussions. It said the companies explored the idea of combining last year but the talks led nowhere. The newspaper reports each cited unidentified people familiar with the situation.