A federal appeals court on Tuesday revived a class-action lawsuit accusing Pfizer Inc of causing tens of billions of dollars of losses for shareholders by misleading them about the safety of its Celebrex and Bextra pain-relieving drugs.

It also said Swain was wrong to conclude that jurors could not find Pfizer liable for statements by G. D. Searle & Co and Pharmacia Corp, which previously made Celebrex and Bextra, that allegedly concealed the drugs’ cardiovascular risks.

The lawsuit began in 2004, and covers investors who bought Pfizer stock between Oct. 31, 2000 and Oct. 19, 2005.

Pfizer’s market value fell by roughly $70 billion from early October 2004 until the day after the class period ended. Tuesday’s decision returns the case to Swain.

In a statement, Pfizer said it “appropriately communicated accurate and science-based information about its medicines to investors and the public at all times and will continue to defend this case vigorously.”

Concerns about the safety of Celebrex and Bextra mounted in late 2004 when rival Merck & Co withdrew its own Vioxx drug because of associated cardiovascular risks.

Pfizer pulled Bextra from the U.S. market the following April, and agreed in September 2009 to pay $2.3 billion to settle a U.S. Department of Justice probe into the marketing of Bextra and other drugs.

Shareholders accused the New York-based company of having concealed tests that began in 1998 and suggested health risks associated with Celebrex and Bextra.

Writing for the appeals court, Circuit Judge Debra Ann Livingston said Swain “went astray” in excluding Fischel’s expert testimony because of his failure to “disaggregate” alleged misrepresentations by Pfizer that may have inflated its stock price from any misrepresentations by Searle and Pharmacia.

“Plaintiffs’ theory is directly contrary to this idea: they argue that Pfizer is liable for all of the artificial inflation related to Celebrex and Bextra because, through its own fraudulent conduct, Pfizer concealed the same information as its predecessors,” Livingston wrote.

In that context, she added, “Fischel’s testimony can be helpful to the jury.”

A lawyer for the plaintiffs had no immediate comment.

In afternoon trading, Pfizer shares rose 8 cents to $31.97.

The case is In re: Pfizer Inc Securities Litigation, 2nd U.S. Circuit Court of Appeals, No. 14-2853.