Nasdaq's $1.8bn (€1.5bn) takeover bid for Instinet stumbled last week after a government investigation, an 11th-hour counterbid and lawsuits from disgruntled shareholders threatened to derail the deal.

Nasdaq agreed to buy the electronic trading platform in April and the offer was thought to be running smoothly. Nasdaq was to buy the group, keep the Inet electronic communications network, and sell Instinet's brokerage to Silver Lake Partners, a private equity firm. The Bank of New York would take over a third division, the Lynch Jones & Ryan brokerage unit.