Alphabet Inc. joined an elite group of companies valued at more than $3 trillion on Monday in the latest sign of improving sentiment for the Google parent.Shares rose as much as 4.3$251.22, resulting in a market capitalization just over $3 trillion. The stock has soared more than 70$1.2 trillion in value over that span.Alphabet joins a short list of other companies valued above $3 trillion, with Nvidia Corp., Microsoft Corp., and Apple Inc. as the only other publicly ...