Teva Pharmaceutical Industries Ltd. helped mastermind a sweeping conspiracy among generic-drug makers to raise the price of hundreds of medicines, according to a new antitrust lawsuit filed by states that stems from a five-year investigation of the companies.

The price fixing resulted “in many billions of dollars of harm to the national economy over a period of several years,” according to the complaint.

Teva’s U.S. shares were bruised in trading on Monday, closing down nearly 15 percent at $12.23 after a rocky day on Wall Street.

More than a dozen current and former executives at top generic-drug makers, including Mylan NV and a unit of Pfizer Inc., were targeted in the lawsuit made public Friday. The suit — filed by 43 states including Pennsylvania and New Jersey — was led by Connecticut.

“I think the evidence is damning. This is a whole gun store of smoking guns,” said Michael A. Carrier, a professor at Rutgers Law School who specializes in antitrust and pharmaceuticals. “There’s literally no one that can defend this story of behavior. It’s very black and white. Price fixing is illegal because it’s so anticompetitive and there are no good reasons for it. “

“Top executives of the nation’s largest generic drug manufacturers conspired to inflate prices at the expense of Pennsylvanians and the American people — in some instances by more than 1,000 percent," said Pennsylvania Attorney General Josh Shapiro. "So we’ve filed this lawsuit to hold them accountable.”

Three of the companies named in the lawsuit — Teva, Mylan and Lannett — have their U.S. headquarters in the Keystone State. At least forty-one generic drug manufacturers are concentrated in the corridor between Philadelphia and New York City. Among the other regional defendants are Actavis, Aurobindo, Breckenridge, Dr. Reddy’s, Glenmark, Greenstone, Par, Pfizer, Sandoz, Taro, Wockhardt and Zydus.

The suit accuses the drugmakers of inflating prices of more than 100 different drugs, significantly broadening a 2016 complaint. In addition to the states, the Justice Department’s antitrust division is conducting a criminal investigation. The unit’s chief said April 30 that charges would be filed, without specifying timing.

About 90 percent of all prescriptions filled in the U.S. are generics.

Dinners, parties and golf

The states say the pharmaceutical companies conspired with one another to fix prices and carve up markets for medicines among themselves, rather than compete on price. Executives used industry dinners, cocktail parties and golf outings to perpetuate the scheme, in addition to communicating through text messages and telephone calls, the complaint said.

The suit names upper-level sales and marketing executives including Maureen Cavanaugh, a former senior vice president for Teva, who is now at Lannett Co., according to the company’s website. James Nesta, Mylan’s vice president of sales, and David Rekenthaler, a former vice president of sales at Teva who is now at Apotex Inc., according to his LinkedIn profile, are also named as defendants.

Mylan president Rajiv Malik was named in a separate complaint filed by state attorneys general in 2017. That complaint is still pending.

As prices for hundreds of generic drugs have risen — with some skyrocketing without explanation — drug costs have sparked outrage from politicians, payers and consumers across the country. The growing frustration and public reports of unexplained and suspicious price increases caused Connecticut to begin its investigation in July 2014, according to the suit. Shortly thereafter, Congress opened an inquiry.

Generic drug manufacturers argued publicly that the increases were due to benign factors. They blamed prices on industry consolidation, FDA-mandated plant closures, or elimination of unprofitable generic drug product lines. Investigators found that the reason underlying many of these price increases was much more straightforward: illegal collusion among generic drug manufacturers.

Company responses

Teva, the world’s largest generic drugmaker, denied the charges.

“The allegations in this new complaint and in the litigation more generally, are just that: allegations,” Kelley Dougherty, a Teva vice president, said in a statement. “Teva continues to review the issue internally and has not engaged in any conduct that would lead to civil or criminal liability.”

Pfizer, whose Greenstone generics unit was named in the suit, said in a statement that it has cooperated with the Connecticut attorney general since being contacted more than a year ago and that “we do not believe the company or our colleagues participated in unlawful conduct and deny any wrongdoing.”

Other companies didn’t respond to requests for comment. Cavanaugh, Nesta and Rekenthaler didn’t immediately respond to messages sent through LinkedIn.

The complaint puts Teva at the center of the conspiracy, saying it colluded with a core group of competitors to follow each other’s price increases. During a 19-month stretch from 2013 to 2015, Teva significantly raised prices on about 112 generic drugs and colluded with its competitors on at least 86 medicines, the states said. While the size of the increases varied, some were more than 1,000 percent.

The states are seeking unspecified damages and penalties from the companies. Potential fines could exceed $2 billion, given that generic drug firms were churning out higher profits during the time in question, said Steven Tepper, an analyst at Israel Brokerage & Investments. That strikes a blow to a company already struggling to pay back $29 billion of debt — a sum almost twice its market value.

“To take this in proportion, that’s about a year’s worth of free cash flow that will have to be thrown out instead of used to reduce the debt,” Tepper said. “The companies will most likely drag this lawsuit out for a number of years and Teva could be in much better shape then than it is in today. But a major fine is still not a nice situation.”

Staff writer Sam Wood contributed to this article.