The cancellation of more than 200 trades on Eurex and the collapse in price of its benchmark equity index contract has raised concerns that one or more market participants tried to manipulate or squeeze the market.

Late on Wednesday, the Swiss-German derivatives exchange was forced to cancel 200 trades in Euro Stoxx 50 and Stoxx 50 futures after a series of trades sent the Euro Stoxx 50 futures contract plunging from 2,400 to 493 in just 45 seconds. Eurex moved quickly to deny reports in the UK press that the collapse was another example of a "fat finger" input error, in which a trader enters the wrong price or size of a trade - raising the prospect of another attempted market squeeze.