Citi has bought an electronic market-maker for $658m (€484m) which analysts said heralded the dawn of a new era of fully electronic trading in stocks.

Citi has agreed to acquire Automated Trading Desk for $102.6m in cash and 11.2 million shares of stock. ATD will operate as a unit of the bank's global equities business and the bank said it will expand ATD's technology and trading expertise to markets around the world which are experiencing similar growth in trading volume and electronic execution.