A Manhattan federal judge has ordered seven U.S. stock exchanges to face proposed class-action claims that they defrauded ordinary investors by quietly enabling high-frequency traders to trade faster and at better prices.

U.S. District Judge Jesse Furman on Tuesday said claims against BATS Global Markets, Nasdaq, the New York Stock Exchange and other defendants had "nudged themselves across the line from conceivable to plausible" and should not be dismissed.

Furman had dismissed the claims in 2015, saying the exchanges were absolutely immune from liability, but a federal appeals court overturned that finding in December 2017.

The exchanges were accused of violating federal securities law by developing and selling high-priced services to provide advantages to favored high-frequency trading customers, while concealing these services from ordinary investors.

High-frequency traders were allegedly afforded access to enhanced data feeds, a greater ability to process complex orders, and permission to locate their servers near the exchanges' own servers so trading signals would be sent faster.

Investors claimed they lost money as a result of the exchanges' manipulative conduct.

"A manipulation complaint must plead with particularity the nature, purpose, and effect of the fraudulent conduct and the roles of the defendants," Furman wrote. "Plaintiffs' complaint ... does just that."

The investors were led by the city of Providence, Rhode Island, pension plans for the city of Boston and the Virgin Islands, and the Plumbers and Pipefitters National Pension Fund, court papers show.

Lawyers for the exchanges did not immediately respond on Wednesday to requests for comment. The investors' lawyers did not immediately respond to similar requests.

High-frequency traders, who use computer algorithms to gain split-second trading advantages, were the subject of Michael Lewis' 2014 best-seller "Flash Boys."

BATS is now owned by CBOE Global Markets Inc, while the NYSE is part of Intercontinental Exchange Inc.

The case is In re Barclays Liquidity Cross and High Frequency Trading Litigation, U.S. District Court, Southern District of New York, No. 14-md-02589.