** Shares of AI software maker C3.ai AI.N fall 2.5% to $38.68 in premarket trading
** KeyBanc Capital Markets downgrades the stock to "underweight" from "sector weight", sets PT at $29
** Brokerage fears large operating losses and potential risk of Microsoft MSFT.O partnership not yielding material results
** Says concerned that consensus revenue estimates for FY26/FY27 "may be too high considering subscription revenue growth excluding upfront license has moderated" to a 1% drop in Q2
** Four of 11 brokerages rate the stock "buy", 5 "hold" and 6 "sell"; their median PT is $40
** Up to last close, stock had risen 38.2% this year
(Reporting by Kritika Lamba in Bengaluru)
((Kritika.Lamba@thomsonreuters.com))