Deutsche Bank is investigating a series of trades that may have improperly generated millions of dollars in personal profits, some at the bank’s expense, for a handful of current and former employees, according to people familiar with the matter.

Among those who internal auditors believe profited from the trades is Colin Fan, these people said. Fan was co-head of Deutsche Bank's investment bank when he left as part of a shake-up in October. The auditors estimate Fan has made $9 million on a roughly $1 million investment.