Sydney: A selloff in global technology shares sent benchmark indexes tumbling from Sydney to London amid heightened concerns about corporate earnings. The dollar halted a rebound.

Samsung Electronics Co. and Tencent Holdings Ltd. had the biggest declines in the MSCI Asia Pacific Index, dragging down tech shares from the highest level since 2000, while ASML Holding NV paced losses in Europe.

US equity futures slumped as dropped in after-hours trading. The yen strengthened against the dollar, while the euro rallied to the highest since January 2015 against the Swiss franc.

US stocks have rallied to records amid signs of solid economic growth globally and as more than three-quarters of S&P 500 companies have delivered earnings that beat forecasts.

Technology shares have led the charge, with companies soaring 22% this year for the best performance among 11 groups in the S&P 500. The sector trades at an average 19 times projected earnings.

“With Amazon’s earnings falling short of estimates, the US market may readjust its expectations," Hideyuki Ishiguro, a senior strategist at Daiwa Securities Co. in Tokyo, said. “Investors are becoming increasingly wary over the historically low volatility levels, with a host of key economic data coming out in the US"

Stocks were rattled in the US on Thursday after JPMorgan Chase & Co. derivatives strategist Marko Kolanovic said the market’s volatility drought could presage protracted histrionics. Attention remains on corporate results ahead of a report on US second-quarter growth.

Financial markets have fluctuated this week following a Federal Reserve statement indicating concern about inflation. Policy makers are expected to begin reducing the Fed’s $4.5 trillion balance sheet in September even as they avoid rushing to raise interest rates. Bloomberg