Shares climbed 7.75% to $297.17 on Wednesday, their third straight gain, topping the previous $280 peak set on 5 May.
The move came in a broadly stronger market, with the S&P 500 up 1.46% and the Dow Jones Industrial Average rising 1.24%.
Trading volume reached 14.5 million shares, above the 50-day average of 10.1 million, though Lam lagged AMD's 18.61% gain and trailed gains by Applied Materials and Analog Devices.
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