(Reuters) — A U.S. judge on Thursday said institutional investors, including BlackRock Inc. and Allianz SE’s Pacific Investment Management Co., can pursue much of their lawsuit accusing 15 major banks of rigging prices in the $6.6 trillion-a-day foreign exchange market.

U.S. District Judge Lorna Schofield in Manhattan said the nearly 1,300 plaintiffs, including many mutual funds and exchange-traded funds, plausibly alleged that the banks conspired to rig currency benchmarks from 2003 to 2013 and profit at their expense.

"This is an injury of the type the antitrust laws were intended to prevent," Judge Schofield wrote in a 40-page decision.

The banks, which sometimes controlled more than 90% of the market, included Bank of America Corp., Barclays PLC, BNP Paribas SA, Citigroup Inc., Credit Suisse Group AG, Deutsche Bank AG, Goldman Sachs Group Inc., HSBC Holdings PLC, JPMorgan Chase & Co., Morgan Stanley, Royal Bank of Canada, Royal Bank of Scotland, Societe Generale SA, Standard Chartered PLC and UBS Group AG or various affiliates.

In their complaint, the plaintiffs accused the banks of improperly sharing confidential orders and trading positions, and using chat rooms with such names as "The Cartel," "The Mafia" and "The Bandits' Club."

Banks were also accused of using deceptive trading tactics such as "front running," "banging the close" and "taking out the filth."

The banks countered that the plaintiffs pointed to no transactions where the alleged manipulation caused losses.

Judge Schofield dismissed portions of some the claims, and dismissed some Allianz plaintiffs from the case.

Lawyers for the plaintiffs did not immediately respond to requests for comment.

The litigation began in November 2018, after the plaintiffs "opted out" of similar nationwide litigation that had resulted in $2.31 billion of settlements with most of the banks.

Those settlements followed regulatory probes worldwide that led to more than $10 billion of fines for several banks, and the convictions or indictments of some traders.

Investors typically opt out of litigation when they hope to recover more by suing on their own.

The case is Allianz Global Investors GMBH et al. v. Bank of America Corp et al., U.S. District Court, Southern District of New York.