A complaint claiming Robinhood Markets and other brokerages of wrongfully blocking retail investors from buying fast-rising "meme stocks," causing a sell-off, was dismissed by a US judge.

Chief Judge Cecilia Altonaga of the federal court in Miami ruled on Wednesday that there was no evidence of an illegal conspiracy to stop GameStop, AMC Entertainment Holdings, Bed Bath & Beyond, and six other stocks from trading on social media.

The brokerages and Citadel Securities allegedly conspired to stop a "short squeeze" that was costing billions of dollars in losses for hedge funds betting on declining stock prices, according to the proposed class action.

The investors said that the late-January trading restrictions left them with "no choice" except to sell at lower prices.

Despite emails between senior Robinhood and Citadel executives lending "some plausibility" to the investors' assertions, Altonaga wrote in her 51-page ruling that they came "far short" of establishing direct evidence of an antitrust conspiracy.GameStop hearing: Robinhood founder defends halt to trading | GameStop | The Guardian

"Are a few unclear and ambiguous emails between two firms in an otherwise lawful, continuous commercial relationship sufficient to shift plaintiffs' claims from conceivable to plausible?" Altonaga penned the piece. "The court disagrees."

E*Trade Financial and four other defendants were also dismissed by Altonaga.

The investors' lawyer, Frank Schirripa, said on Thursday that they were unhappy, but that they anticipated revising their complaint in the coming weeks.

"This further indicates that the conspiracy hypothesis of collusion has no basis in actuality," Robinhood said in a statement.

Citadel expressed satisfaction with the decision. E*Trade did not respond to a request for comment. In a separate proposed class action, Robinhood is accused of negligence.

The craze for meme stocks has been fanned by online platforms such as Reddit and Twitter by investors.

Because of the COVID-19 outbreak, many people traded from home using brokerages that had abolished trading commissions.

The US Securities and Exchange Commission claimed in a study this month that the stock market structure "absolves short sellers." that markets performed admirably during the turbulence The regulator made no recommendations for policy adjustments.

In re January 2021 Short Squeeze Trading Litigation, No. 21-MD-02989, U.S. District Court, Southern District of Florida.