(Bloomberg) -- For about a year, investors have bid up megacap tech shares on the theory that their exposure to artificial intelligence will usher in a new era of elevated growth and efficiency. Now the companies need to prove it.Most Read from BloombergMusk Says First Neuralink Patient Received Implant in BrainTraders Line Up for ‘Once-in-a-Generation’ Emerging Markets BetBlackstone Is Building a $25 Billion Empire of Power-Hungry Data CentersTrump Cash Stockpile at Risk From $450 Million Dual