Deutsche Börse, the Frankfurt-based stock exchange, faces further shareholder opposition after its biggest domestic investor, Union Investment, called for bosses to pay a one-off dividend and abandon its planned share buyback scheme.

Union Investment, the group's fourth largest shareholder with a 4% stake, proposed that the exchange return the full €226.8m ($296.4m) in earnings it had retained from 2004. The proposal was posted as a counter-action on Deutsche Börse's website on Thursday.