TA Associates, a Boston-based private equity firm, has taken a $50m (€40.8m) stake in Creditex, in a deal understood to value the online credit derivatives trading platform at close to $150m.

Creditex, founded by former Deutsche Bank staff Sunil Hirani and John McEvoy in 1999 when the credit derivatives market was worth $500bn, is believed to have the lion's share of a market now worth over $8.5 trillion.