Nasdaq today remained tight-lipped over a growing threat to its latest attempt to take over a European exchange after a newly-formed Middle Eastern competitor snapped up a quarter of Swedish target OMX in a raid on options and shares.

Nasdaq, which is the largest shareholder in the London Stock Exchange but saw its hostile bid for the group lapse without success six months ago, agreed a deal to take over OMX in May, since when the deal has been dogged by speculation about a counterbid from Dubai.