(Reuters) - Google-parent Alphabet hit a market capitalization of $3 trillion for the first time on Monday, riding on renewed optimism around artificial intelligence and a favorable antitrust ruling. Class A shares of the company were up 4.6$251.88, while Class C shares climbed 4.5% to $252.3 - both trading at record highs. Alphabet joined companies including iPhone maker Apple and Microsoft that have also clinched valuations of$3 trillion. AI-leader Nvidia has crossed the $4 trillion mark. The lat ...