Shares in the London Stock Exchange fell over 12% in trading this morning after it admitted it will suffer a delay in its bid to compete with the new breed of "dark pool’ trading systems following the collapse of Lehman Brothers, with which it was setting up a rival platform.

Europe's largest exchange said its dark pool trading platform, called Baikal, will go live "late" in the second quarter of next year, having initially set a launch date of March. It set up Baikal as a joint venture with Lehman Brothers five months ago.