Asian markets recovered some of the losses suffered in a morning sell-off Tuesday but investors remain on edge ahead of a key Federal Reserve policy meeting.
News of a massive data breach at Facebook fuelled fears of a regulatory crackdown on the technology sector, sparking plunges in New York Monday.
The scandal at the social media giant further fuelled anxiety among investors already fretting over possible US interest rate rises and Donald Trump's protectionist rhetoric, which has sparked talk of a global trade war.
Reports said Cambridge Analytica, the analysis firm hired by Donald Trump's 2016 presidential campaign, stole data from 50 million Facebook user profiles to help design software to predict and influence voters' choices.
Stephen Innes, head of Asia-Pacific trading at OANDA, warned: "This security breach could end up being a significant turning point for the social media and network portal."
The news hammered tech giants, with Facebook plunging 6.8 percent while other household names were also hit -- including Apple, Google-parent Alphabet and Netflix -- by regulatory concerns.
- Pound gains -
"The adults are starting to realise that the altruistic kids who started some of these tech behemoths are either unwilling or unable to deal with the fact that the companies they wrought and thought were a force for good can be manipulated by those who seek to do ill," said Greg McKenna, chief market strategist at AxiTrader.
The US losses filtered through to Asia in early trade but tech firms in the region bounced back as the day wore on. Hong Kong-listed internet giant Tencent and AAC Technologies moved into positive territory, as did Samsung in Seoul. However, while Sony pared losses in Tokyo it ended lower.
Broader markets were mixed, having all started down. Japan's Nikkei dipped 0.5 percent and Sydney slipped 0.4 percent.
But Hong Kong added 0.1 percent and Shanghai ended up 0.4 percent, with investors cheered by comments from Chinese Premier Li Keqiang calling for the US to avoid a trade war.
Li said the the United States should not act "emotionally" over trade frictions, which have rattled markets, just as Trump considers new actions against Beijing over its "theft" of US intellectual property.
Singapore was 0.2 percent higher and Seoul climbed 0.4 percent. Wellington, Manila, Taipei and Jakarta were all down.
Investors are keeping a close watch on the Fed's meeting this week, seeking clues about its timetable for tightening monetary policy. Opinion is split on the number of rate rises it will announce this year, with some forecasting three and others saying four.
Market-watchers warn that a G20 meeting of finance ministers in Argentina could also revive tensions on international trade after Trump unveiled his controversial tariffs this month.
On currency markets the pound extended gains against the dollar after Britain and European Union leaders agreed a post-Brexit transition deal that will buy businesses and citizens time to adjust to life after the divorce.
London rose 0.5 percent, while Frankfurt and Paris each added 0.2 percent.
- Key figures around 0820 GMT -
Tokyo - Nikkei 225: DOWN 0.5 percent at 21,380.97 (close)
Hong Kong - Hang Seng: UP 0.1 percent at 31,549.93 (close)
London - FTSE 100: Up 0.5 percent at 7,075.50
Euro/dollar: UP at $1.2343 from $1.2290 at 2100 GMT
Pound/dollar: UP at $1.4055 from $1.3942
Dollar/yen: UP at 106.46 yen from 106.01 yen
Oil - West Texas Intermediate: UP 56 cents at $62.62 per barrel
Oil - Brent North Sea: UP 55 cents at $66.60 per barrel
New York - Dow: DOWN 1.4 percent at 24,610.91 (close)