Proprietary trading firms accounted for nearly a third of activity on Deutsche Bank's US dark pool in 2015, according to disclosures by the German group which make it one of the first banks to reveal highly-sensitive information into trading on its electronic platform.

Dark pools, which account for up to 18% of overall US equity trading, are being probed by regulators and face new legislation but many banks are choosing to act ahead of the rules by being more transparent about how they operate the venues.