A U.S. Senate committee detailed in an investigative report Wednesday how drug companies were exploiting the market by acquiring decades-old crucial medicines and suddenly raising their prices astronomically.

“We must work to stop the bad actors who are driving up the prices of drugs that they did nothing to develop at the expense of patients just because, as one executive essentially said, ‘because I can,’” said Sen. Susan Collins, a Maine Republican, who chairs the Senate Aging Committee.

Over the last year, the committee investigated four drug companies, which it said had all used a similar business model that included egregious price hikes to maximize profits.

Here are some of the key findings in the committee’s 131-page report on those companies, which included Turing Pharmaceuticals, Retrophin, Valeant Pharmaceuticals International and Rodelis Therapeutics.

The companies raised prices — not to fund research to discover new drugs — but to boost profits for executives and investors. In essence, they operated more like hedge funds than traditional pharmaceutical companies.

Turing, headed by executive Martin Shkreli, bought Daraprim, a 62-year-old medicine for a deadly parasitic disease, on Aug. 7, 2015, and raised the price overnight from $13.50 to $750 a pill.

When asked by investors about the expected revenues from the drug, Shkreli wrote, “I think it will be huge. . So 5,000 paying bottles at the new price is $375,000,000 — almost all of it is profit, and I think we will get three years of that or more. Should be a very handsome investment for all of us.”

The company’s programs to help patients afford the drugs weren’t charities, but a way to increase profits on their monopolies.

The committee said Valeant offered a program that covered the cost of co-pays for privately-insured patients because executives knew it would reduce patients’ “incentive to complain to the press about Valeant’s outrageous price increases.”

By increasing prices rapidly, but covering patients’ co-pays, the companies could still make big profits, the committee said.

They used the example of a drug priced at $100,000 that cost $10,000 to manufacture and distribute, leaving a potential profit of $90,000. If the company covered the patient’s $20,000 co-pay, the insurance company still paid $80,000 for the drug, resulting in a $70,000 profit for the company.

The patient assistance programs were a key method that Valeant used in raising the price of Cuprimine, used since 1956, and Syprine, developed in 1969, the committee said. Both drugs are used to treat Wilson disease.