Alphabet shares rallied nearly 6% to a record high on Monday after Berkshire Hathaway's new stake provided an endorsement of the tech giant's artificial intelligence efforts amid heightened worries over a looming bubble.

Shares of Alphabet ( GOOGL +3.09%) ( GOOG +3.10%) popped on Monday, following news that Warren Buffett's Berkshire Hathaway had taken a sizable stake in the internet search leader. As of 3:25 p.m. EST, Alphabet's stock price was up about 3% after rising as much as 6% earlier in the day.

U.S. stocks were struggling for direction in morning trading on Monday as investors awaited a number of key data releases later this week, including the September jobs report and Nvidia Corp.'s earnings.

See why analysts are bullish on Alphabet Inc. amid strong fundamentals and growth, but why its valuation now reflects a growth premium. Click for my GOOGL update.

Google plans a $40 billion Texas data center investment, creating thousands of jobs as tech companies compete for AI infrastructure capacity.

Alphabet Inc. shares jumped nearly 6% on Monday, hitting a record high, after Berkshire Hathaway Inc. disclosed a multibillion-dollar position in the Google parent — a rare endorsement from the value-investing conglomerate known for its caution toward technology stocks.

Alphabet is upgraded to Buy with a $322 price target, driven by robust Google Cloud growth and AI integration across platforms. Learn more about GOOG stock here.