Republican Senate candidate from Pennsylvania, Dr. Mehmet Oz, has financial ties to at least two pharmaceutical companies that supply hydroxychloroquine, an antimalarial drug he circulated as a possible treatment for Covid-19.

Oz, a physician and veteran television host who is up against Democrat John Fetterman in the race for the Pennsylvania Senate seat, owns with his wife at least $615,000 in Thermo Fisher Scientific stock, according to its financial disclosure. Thermo Fisher Scientific’s website lists hydroxychloroquine sulfate as one of the available products. It’s unclear when Oz and his wife bought the stock or if they owned it, as Oz promoted hydroxychloroquine as a Covid treatment early in the pandemic.

Oz and his wife also own between $15,001 and $50,000 in McKesson Corporation stock, according to the disclosure. According to the FDA, the company labels and sells hydroxychloroquine sulfate. It’s also unclear when they bought McKesson stock.

Hydroxychloroquine sulfate is the anti-malarial drug commonly known as hydroxychloroquine, according to the Food and Drug Administration. Doctors across the country, helped in part by support from former President Donald Trump and conservative media figures, have been offering the drug to patients as a Covid treatment, despite its questionable effectiveness against the virus.

Oz’s financial ties to a manufacturer and distributor of the drug, and his promotion of it as a potential Covid treatment, raise questions about what he would benefit from its wider use during the pandemic. If he wins the Senate election, he could also face conflicts of interest as Congress grapples with a still-evolving coronavirus pandemic.

In a statement responding to CNBC questions about Oz’s ties with companies that manufacture or distribute hydroxychloroquine, including when he and his wife bought shares in Thermo Fisher Scientific, Oz campaign spokeswoman Brittany Yanick, does not affect the financial interests of the candidate.

“At the beginning of the pandemic, Dr. Mehmet Oz with healthcare professionals worldwide who are considering hydroxychloroquine and azithromycin as viable treatment options for critically ill COVID patients. He offered to fund the clinical trial at Columbia University,” she said.

The FDA has approved hydroxychloroquine to fight malaria but warned that it “has not been shown to be safe or effective for treating or preventing COVID-19.”

Oz took bold steps early in the pandemic to promote its use as a treatment. He urged Trump administration officials in 2020 to support a study he wanted to fund at Columbia University Medical Center on the effect of hydroxychloroquine on Covid-19 patients, according to emails obtained by the select subcommittee of the House of Representatives on the coronavirus crisis have been received and published.

Oz also has ties to a third company, which it says has divested hydroxychloroquine from its US portfolio.

Sanofi, which is headquartered in France and previously manufactured hydroxychloroquine, supported Oz’s nonprofit HealthCorps for years, according to the group’s annual disclosure reports. Between 2009 and 2018, Sanofi was listed as either a sponsor or donor in kind to the Oz-funded group, which owns aims to help teenagers with their health and well-being. In 2013, Sanofi is listed as one of the group’s “School Sponsors”. HealthCorps’ website states that a school sponsor must donate $100,000 to qualify.

Sanofi announced in April 2020 that it would donate 100 million doses of hydroxychloroquine to 50 countries around the world as studies evaluated the drug’s effectiveness in treating Covid-19.

A spokesman for Sanofi told CNBC that the company was not involved in Oz’s comments about Covid-19 or hydroxychloroquine. He explained that Sanofi divested hydroxychloroquine from its US portfolio in 2013 and was investigating the drug’s use as a potential way to fight the virus early in the Covid pandemic. After it was deemed ineffective against Covid-19, the company’s work on it was suspended.

The spokesperson also explained that the company’s last financial contribution to HealthCorps was in 2011. The company representative later corrected himself in a follow-up email to CNBC after the publication of this story, saying that 2013 was actually the last year that Sanofi made a financial donation to HealthCorps.

Oz’s ties to companies that would benefit from wider use of hydroxychloroquine could pose problems for the Republican if he wins the Senate seat. Kedric Payne, an ethics attorney at the Campaign Legal Center, told CNBC in an email that Oz could choose to walk away from the companies if he defeated Fetterman in November.

“He could have a rude awakening if elected because ethics rules could bar him from the job. Senators cannot use their positions to promote goods or services that benefit them financially,” Payne said. “Oz could voluntarily divest the shares if elected or stop promoting anything tied to his shares.”

A spokesman for Thermo Fisher Scientific declined to comment. A McKesson representative did not respond to a request for comment prior to publication.

Since launching his campaign late last year, Oz has downplayed warnings from the FDA and other experts against the use of hydroxychloroquine as a Covid treatment. He suggested political animus against Trump endorsing the drug as a treatment and Oz in the Senate election, motivating criticism of the drug as a way to combat Covid.

“Well let me say this real quick, I really don’t know if it works or not, we haven’t been able to prove to this day if it works [hydroxychloroquine] works or not, which is a shame because we should have known by now whether a cheap 70-year-old drug used by a billion people works or not,” Oz said at a campaign event earlier this year. “But we don’t know. t which is a problem in itself. However, I mentioned it and then President Trump mentioned it in a press conference and suddenly the whole world hated hydroxychloroquine without testing it, without knowing it.”

Before launching his campaign, Oz championed hydroxychloroquine more explicitly. During an interview with Fox News in March 2020 at the height of the pandemic, Oz said that “hydroxychloroquine has a role” in fighting the virus. An on-screen graphic while Oz was being interviewed called the anti-malarial drug “promising” as a treatment option for Covid-19.

Oz also sought White House help to get the hydroxychloroquine trial going, which he wanted to fund at Columbia, where he was once vice chairman of the department of surgery. He has since said the study never got off the ground.

The Pennsylvania nominee’s communications with White House officials were released last month by the House’s select subcommittee on the coronavirus crisis. In an email dated March 2020 Deborah Birx, former Trump White House coronavirus response coordinator, told Oz he would recruit patients and pay for the hydroxychloroquine trial himself.

Also in March 2020, Oz Trump’s son-in-law and adviser Jared Kushner emailed that “we must make the completion of this study a national priority and insist on immediate enrollment,” according to correspondence obtained by the House Committee and has published. Kushner replied to Oz the same day, “What do you recommend to speed it up?”

The New York Post reports that Oz spent $8,800 on hydroxychloroquine tablets for the study at the time and offered to spend $250,000.

Oz, during his campaign for the Pennsylvania Senate seat, accused then-New York Governor Andrew Cuomo of stopping the study after effectively banning the anti-malarial drug as a Covid treatment.

Oz’s financial ties could pose a bigger problem for him if he wins the Pennsylvania race, one of a few contests to decide which party will control the Senate next year. A Real Clear Politics poll average shows Fetterman leading Oz by almost 7 percentage points.

Share ownership in Congress will come under increased scrutiny. Some lawmakers in Congress have proposed a ban on individual stock deals that would require lawmakers to invest assets in a blind trust or to divest them outright.

Business Insider has identified at least 71 lawmakers who have violated the Stop Trading on Congressional Knowledge Act, or STOCK Act. The law aims to prevent members of Congress from trading stocks using inside information gained from their work as legislators.

By and large, however, members of Congress had little impact on lucrative stock deals.