Traders work on the floor of the New York Stock Exchange shortly after the opening bell in New York City, November 21, 2019.

Lucas Jackson | Reuters

Technology stocks, a longtime sector leader, once again lifted the broad market to records.

The Technology Select Sector SPDR Fund, one of the biggest tech exchange-traded funds with $25.7 billion assets under management, surged more than 1% to an all-time intraday high on Monday, bringing its year-to-date gains to 46%.

With the help of the tech rally, major U.S. stock indices — the S&P 500, the Dow Jones Industrial Average and the Nasdaq Composite — all refreshed their records.

Tech was the best-performing sector among the 11 S&P 500 groupings, led by Micron Technology and Western Digital which traded 4.5% and 6.9% higher. Micron is trading at its 52-week high, on pace for its best day in two months.

Micron and Western Digital surged Monday on upgrades from Susquehanna International Group. The equity research firm upgraded Western Digital on the expected ramp-up of the 5G smartphone build cycle. The firm also recommended Micron as it sees an attractive risk-reward for the chipmaker.

However, one of Wall Street’s top technology analysts is warning that the sector has gotten too expensive. In a note to clients on Monday, Bernstein’s Toni Sacconaghi pointed out that the sector is currently trading at 22 times earnings, the highest level for the group in 15 years.

“Given elevated valuations and elevated expectations for high priced stocks, we believe risk remains high in tech,” Sacconaghi said.

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