The case was later settled, and Mr. Chiklis did not return calls for comment. But Mr. Smith, who replaced Mr. Chiklis, said Mr. Collins rarely weighed in on company business.

Mr. Collins had an estimated net worth of $43.5 million in 2017, according to Roll Call. When the company’s stock plunged last year, federal prosecutors have said Mr. Collins did not sell his own shares because he knew he was under investigation. He likely lost millions. According to his 2017 disclosure form, filed in April, Mr. Collins owned between $1 million and $5 million in Innate Immunotherapeutics stock.

In June of this year, financial disclosure records show he sold between $15,000 and $50,000 in stock in Innate, his only reported sale of the stock since it lost most of its value.

Oddly enough, some of the other Republican congressmen or their spouses who invested in Innate did so in January 2017, the same month that Mr. Price’s investments came under public scrutiny. Representative John Culberson of Texas bought $13,982 in shares, and lost $9,194 when he sold it in June of last year, two weeks before the company announced that the drug trial had failed.

Mr. Mullin of Oklahoma made the largest investment; between $100,001 and $250,000, according to his financial disclosure form. He did not list a sale, nor did Mr. Long of Missouri, who invested between $15,001 and $50,000, according to his report. Colorado Representative Doug Lamborn, whose wife had purchased between $15,001 and $50,000, reported a sale on June 27, of less than $1,000, suggesting that the couple lost most of the investment.

Representative K. Michael Conaway of Texas reported making two investments of between $1,000 and $15,000 in Innate, around the same time last year.

Since its drug trial failed, Innate Immunotherapeutics has abandoned its multiple sclerosis treatment and announced it had acquired a company that is studying cancer drugs.

Its stock is currently trading at less than 20 cents per share.

In his interview last year with ethics investigators after the M.S. drug trial failed, Mr. Collins sounded a note of regret over his proselytizing for the stock. Of his friends, he said, “everyone heard the presentation,” and, he added, “ultimately, it failed, so obviously they should’ve asked more questions than they did.”