Fresh blow to TCI as analyst joins rival The Children's Investment Fund has lost another of its stars to rival hedge fund Thélème Partners in a sign of tensions among top managers at the activist investor. Oscar Hattink, a portfolio manager at the $6bn TCI and a firm partner since 2008, resigned last year, leaving the firm in August. He has now surfaced as a partner at Thélème, people familiar with the matter told the Financial Times. Mr Hattink joins six other ex-TCI managers and analysts at Thélème which was launched two years ago by TCI's co-founder Patrick Degorce. Mr Degorce set up the firm after disagreements with Christopher Hohn, TCI's head and one of the hedge fund industry's most enigmatic and publicity-shy figures. Under Mr Hohn, TCI carved a big reputation at the height of the boom for earning its investors outsized returns - more than 40 per cent annually on average, in the years up to 2007 - and taking on some of the biggest companies in a spate of sometimes fraught boardroom battles. Mr Hohn has donated almost all of his personal wealth generated through TCI - estimated at in excess of £1bn - to children's charitable initiatives through an endowment run by his wife, Jamie, making him the UK's biggest philanthropist. After weathering losses in 2008, TCI faced an uphill battle to make back its investors" money. Although the hedge fund, which has only a handful of partners, performed strongly since the crash, it has suffered defections of top staff. Thélème's founder Mr Degorce, a French naval officer who had spearheaded TCI's controversial activist investments in Deutsche Börse and ABN Amro before the crash, left TCI in early 2009, "for personal reasons," and was soon followed by fellow co-founding partner Snehal Amin, the hedge fund's main US equities analyst. John Ho, TCI's head of Asia, also left that year. John Sheridan, who replaced Mr Degorce as TCI's lead finance analyst, also subsequently left the firm along with Timothy Keough, Robb LeMasters and Rishi Sunak only to all end up at Thélème. Stuart Powers, another senior TCI analyst, left in January 2011 and is in the process of launching his own new hedge fund, Hengistbury Investment Partners. A lawsuit filed by TCI against Mr Hattink in January - and subsequently dropped - sheds a rare light on to the sums involved in the trading of such top hedge fund talent: the 33-year old Mr Hattink's contributions to TCI's investment returns in 2010 earned him a $5m bonus, according to TCI's complaint in the suit. Mr Hattink declined to comment. TCI could not be reached for comment.