UK activist hedge fund The Children’s Investment Fund Management has taken a stake of almost 1% in the CME Group and a smaller stake in New York Mercantile Exchange Group as the two trading groups struggle to persuade shareholders to back their proposed $9bn (€5.8bn) merger.

TCI’s 520,000 shares in CME Group, 0.95% of the company, were worth almost $250m at the end of last week.