Wall Street’s final holdout on Microsoft stock finally joined its peers by upgrading shares to Buy, calling the technology company a clear artificial-intelligence beneficiary. Guggenheim Securities upgraded Microsoft shares to Buy from Neutral and issued a price target of $586 in a research note Monday. Microsoft stock was up 1.6% to $531.78 in premarket trading Monday, while futures have advanced 0.5%, futures have risen 0.8%, and futures have gained 1.3%.