Shares of Alphabet, Google's parent, touched an all-time high Monday of $293.95, before giving back some of those gains, after Berkshire Hathaway disclosed it bought nearly 18 million shares valued at over $4 billion in the third quarter. Ticker Security Last Change Change % GOOGL ALPHABET INC. 284.40 +7.99 +2.89%

The move served as an endorsement of the tech giant's artificial intelligence efforts amid heightened worries over a looming bubble. Plus, it is one of the final major investments by the conglomerate under Warren Buffett and marks a rare foray into the industry by tech-averse Berkshire.

The vote of confidence comes as broader sentiment on tech has turned cautious, with several business leaders and experts warning that the AI frenzy driving up tech stock prices has detached

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