If Deutsche Börse thought its bruising battle with The Children’s Investment Fund would be its last hedge fund headache, TCI is back with some migraine-inducing news.

The London activist shop and fellow hedge fund Atticus Capital have served notice that the ouster three years ago of Börse CEO Werner Seifert, chairman Rolf Breuer and half of its supervisory board over the its bid for the London Stock Exchange may have been only the beginning. Annoyed that Börse shares have fallen by almost half this year, the hedge funds say they are working together to boost shareholder value.

“This may include seeking to change some of the members of the supervisory board in order to ensure leadership and urgency regarding any appropriate options,” the hedge funds said in a joint statement.

The hedge funds collectively hold 19% of the Börse’s voting rights.

The news that longtime antagonist TCI was being joined by Atticus must have been a rude surprise to some at the Börse: In January, before the precipitous decline in the exchange’s fortunes, Atticus pronounced itself “pleased with the company’s performance, ongoing cost-cutting measures and share buybacks.”

The TCI-led effort to derail the Börse’s proposed takeover of its London counterpart helped fuel a wave of anti-alternative investments sentiment in Europe.