New York State attorney general is suing London-based banking giant Barclays PLC as part of an ongoing campaign against predatory high-frequency trading (HFT), alleging the firm deceived prospective clients for its dark pool and didn’t protect them from high-frequency traders, as it had promised.

State attorney general Eric Schneiderman announced that he has filed a lawsuit against Barclays concerning the operation of its dark pool and other aspects of its electronic-trading business. The complaint alleges that the firm promised dark pool clients that it had adopted special safeguards to protect them from “aggressive” or predatory high-frequency traders, but that it actually operated its dark pool to the benefit of HFT.

“The facts alleged in our complaint show that Barclays demonstrated a disturbing disregard for its investors in a systematic pattern of fraud and deceit,” said Schneiderman. “Barclays grew its dark pool by telling investors they were diving into safe waters. According to the lawsuit, Barclays’ dark pool was full of predators — there at Barclays’ invitation.”

The complaint alleges that Barclays falsified marketing material purporting to show the extent and type of HFT in its dark pool, among other things. It also claims that the bank heavily promoted a service entitled liquidity profiling, which Barclays had claimed would root out predatory HFT and hold traders accountable.

Instead, the complaint says that the bank never prohibited any trader from participating in its dark pool, regardless of how predatory its activity was determined to be; that it did not regularly update the ratings of HFT firms monitored by liquidity profiling; and, that it “overrode” certain liquidity profiling ratings to assign safe ratings to traders that were not.

The lawsuit also alleges that the bank actually operates its dark pool to favour high-frequency traders and that it has actively sought to attract them by giving them systematic advantages over others trading in the pool. The complaint seeks unspecified monetary damages and injunctive relief against Barclays.

None of the allegations have been proven. In turn, Barclays issued a statement in response to the lawsuit saying it takes the allegations “very seriously” and that it has been co-operating with the New York state attorney general and the U.S. Securities and Exchange Commission, as well as examining the issue internally. “The integrity of the markets is a top priority of Barclays,” it said.