By Gregor Stuart Hunter

Asian stocks opened lower Tuesday after tech shares fell sharply in the U.S. overnight due to concerns about whether Facebook Inc. did enough to stop improper access and handling of user data.

The Nikkei Stock Average opened 0.8% lower while Australia's S&P ASX 200 sank 0.6%. South Korea's Kospi sank 0.3% as Samsung Electronics dropped 0.6%.

The Asia declines followed sharp losses for the tech sector in the U.S. Facebook shares plummeted 6.7% and slid another 1.5% in after-hours trading after investors learned Cambridge Analytica, a firm that helped President Donald Trump's 2016 election campaign, had collected and used without permission data from the accounts of millions of users. Cambridge Analytica has said it complied with Facebook's rules.

The Nasdaq Composite fell 1.8%, leading a 1.4% decline for the S&P 500.

Funds tracking the MSCI Emerging Markets Index, which gives a 27% weighting to technology companies--many of them in China, South Korea and Taiwan--also sold off Monday.

Short sellers trading tech stocks including Facebook, Apple Inc., Amazon.com Inc., Netflix Inc. and Alphabet Inc.'s Google made mark-to-market profits of $980 million from Monday's declines, wrote Ihor Dusaniwsky, managing director for predictive analytics at S3 Partners. The size of the stocks in market benchmarks could magnify broader selling.

"With so many of these stocks in passive investment vehicles such as ETFs and funds, these stocks are prone to accelerated negative returns" after significant market downturns, he wrote.

Bond markets and currencies were broadly unchanged. The yield on the U.S. 10-year Treasury note was last up 0.01% at 2.8573%, while the ICE U.S. Dollar Index, which tracks the dollar's strength against a basket of six major currencies, was up 0.1%. The dollar last bought Yen106.0790.

Baidu Inc. shares fell 3.6% on Monday, leading declines among U.S.-listed China stocks. Uber suspended its self-driving car program Monday after the first known fatality from an autonomous vehicle. Baidu is among the companies attempting to bring the technology to China.

Write to Gregor Stuart Hunter at gregor.hunter@wsj.com

(END) Dow Jones Newswires

March 19, 2018 22:05 ET (02:05 GMT)

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