A multibillion-dollar payday for Wall Street lawyers has gotten off to a rocky start.

A highly anticipated class-action antitrust case accusing 22 banks of rigging the very bedrock of the US financial system was criticized by a judge on Monday for lacking specifics, but gave lawyers plenty of time to find them.

Manhattan federal Judge Paul G. Gardephe told attorneys for the 55 plaintiffs he had doubts that the initial complaints “make out a plausible case of collusive or manipulative conduct,” Judge Gardephe said.

The plaintiffs, mostly institutional investors, accuse the banks of rigging the US Treasury markets to sell the debt for higher prices to clients.

The three law firms who are temporary lead co-counsel are Quinn Emanuel, Cohen Milstein and Labaton & Sucharow.

Lawyers say that a settlement could be upwards of $5 billion if a trial gets decided in the plaintiffs’ favor.

The civil suit is kicking off while US and European prosecutors are investigating their roles in setting debt prices.

While the investigation began in June of last year, settlement talks aren’t expected to begin until December at the earliest, one source told The Post.