High-speed trading firms revolutionised stock trading in the US, but many have faced challenges in Asian markets.

Most regulators in the Asian-Pacific region, eager to protect individual investors and the dominant exchanges, have declined to implement the changes that would open many stock markets to profitable high-speed trading. And a number of trading glitches in the US-most notably the May 2010 "flash crash," in which the Dow Jones Industrial Average lost about 1,000 points in minutes before recovering-has made them more reluctant.