Atticus Capital has put its entire stake in Deutsche Börse, the German exchange, into a special limited vehicle to block redemptions by clients and boost its negotiating strength with management.

The stake has lost over half ($1.5bn) in value since the beginning of the year.

While a so called 'side pocket' is a commonly used structure for illiquid investments such as property and private equity, investors are concerned that a highly liquid stock like Deutsche Börse is being put into such a vehicle. Clients who redeem from the main fund have to retain their holding in the side pocket until it comes to an end.

Atticus argues that in their negotiations with the board of the Deutsche Börse they wanted to be able to represent themselves as a solid, long term investor.

Atticus had so far negligible withdrawals. The Atticus European fund is down 33 per cent and Atticus Global is down 25 per cent so far this year.