** Shares of Advanced Micro Devices AMD.O gain 18% to $419.50 in premarket trading

** The chipmaker on Tuesday forecast Q2 revenue above Wall Street expectations, helped by strong AI chip demand as cloud firms ramp up AI spending

** Bernstein upgraded stock to "outperform" from "market perform" rating; says agentic AI boom makes AMD's expectation of a sharply larger addressable market more plausible, with its competitive product lineup positioning it well to benefit

** Firm said it expects Q2 server CPU revenue to grow more than 70%

** Following the results, at least 17 brokerages raised price target on the stock, according to data compiled by LSEG

** 52 analysts rate the stock "buy" on average; median PT is $340 - LSEG data

** As of last day's close, stock up 65.8% YTD