New | Barclays the target of US high-speed trading probe

New York Attorney General Eric Schneiderman's 10-month investigation into high-speed trading has so far led to one big target: Barclays.

Almost a year after Schneiderman made a splash with subpoenas of six high-frequency trading operations, the names of some of these firms cropped up in documents filed this week in the state court in Manhattan.

The firms are not defendants, though. They are listed as part of Schneiderman's proposed updated complaint against Barclays, which ran the private trading venue, or dark pool, where the firms traded.

Schneiderman's suit does not allege any wrongdoing by the high-frequency trading firms. Its focus, instead, is whether Barclays lied to its customers about what such firms were doing inside Barclays' dark pool, one of Wall Street's largest in-house trading platforms.

"High-frequency trading and dark pools are legal businesses and can be beneficial to the market," said Deborah Meshulam, a partner at DLA Piper who specialises in securities enforcement. "Unless there are changes in the regulations, then it is hard to say just how many high-frequency-trading related cases will come to light."

Dark pool trading accounted for 15 per cent of total US volume in the third quarter, according to latest figures from research firm Tabb Group.