At Oklahoma senator Markwayne Mullin’s swearing in as Homeland Security secretary, Donald Trump did what he tends to do at ceremonies: wandered. He bragged about his own margins in the Sooner State, complimented one of Mullin’s sons on his “good genetics,” then returned to the point — Mullin, Trump said, had succeeded in business because “everything he’s touched, he turns to gold.”

The line is on-brand for Trump, who was right about Mullin’s business prowess. Before entering politics, Mullin and his wife Christie turned his family’s struggling plumbing business into a statewide home services empire. He was a multimillionaire when he first won a House seat in 2012. His net worth climbed again after he sold a majority stake to a private equity firm in late 2021, then reinvested the proceeds across real estate and a sizable portfolio of stocks and other assets. Today, Forbes estimates that he is worth around $60 million—12 times the fortune of his predecessor, Kristi Noem.

That figure isn’t airtight. Federal officials disclose their assets in ranges, not exact figures, making true precision impossible. Mullin’s borrowing also complicates the picture. In 2024, he opened a line of credit at 6.1% interest whose size is somewhere between $5 million and $25 million. He also discloses five additional loans taken out in the last three years. Four are from Arvest Bank, owned by the billionaire Walton family, whom he apparently owes between $3.5 million and $16 million at 6.75% interest, according to his most recent disclosure. Robson and Jim Walton both gave to Mullin’s Senate campaign in the last two years.

Forbes dug into public records to narrow down his real estate holdings, modeled how much he may have made in selling Mullin Plumbing and examined years of financial disclosures to arrive at our $60 million figure. A DHS spokesperson declined to answer specific questions about Mullin’s net worth, sale of his business and debts, instead sending a statement describing him as “not your typical politician” and touting his commercial success.

Mullin was born in 1977 and grew up in eastern Oklahoma, near the Arkansas border. He still lives on and owns a 1,600 acre family ranch that advertises itself as an agricultural business as well as “the perfect venue for your corporate event, private party, elopement or wedding reception.” Mullin reported no recent income from the ranch, but Forbes estimates the property is worth about $8 million.

Mullin met Christie in high school. The pair both attended college, but left when Mullin’s father Jim fell ill and the family’s drain and septic servicing business was struggling. “The people he trusted had run the company into the ground,” a clean-shaven Mullin said in a 2012 address shortly before being elected to Congress. “The company was carrying more than a half million dollars in debt, and $250,000 of it was immediately past due.”

They turned it around, he claims, within four years, and the 2000s saw Mullin Plumbing expand rapidly into a full-service plumbing company. Mullin purchased the enterprise from his father in 2007, according to a 2013 financial disclosure that lists a liability, with Jim as the creditor, worth between $500,000 and $1 million.

In 2011, Mullin pivoted to politics, leaving day-to-day operations to two longtime managers. He told the Black Rifle Coffee Podcast in 2024 that his eyes turned toward Washington when the Environmental Protection Agency proposed a new regulation that would have put his water treatment company, Mullin Environmental, out of business. (His former campaign manager told the Washington Post in March that Mullin was also motivated by the Affordable Care Act’s mandate that he provide his employees with health insurance.) In his first race for an eastern Oklahoma congressional seat, he loaned his campaign over $250,000—funds the campaign repaid over the following election cycles. Mullin won in 2012 by almost 20 points, turning a House seat historically held by conservative Democrats as red as his company’s headquarters.

On his first disclosure, he reported assets, including eight companies, worth between $2.8 million and $9.1 million. Even after entering office, he continued to report significant income from those businesses. In 2020, the year before he sold, he declared between $2 million and $10 million in income from Mullin Plumbing and between $100,000 and $1 million, each, from its HVAC and septic divisions.

In late 2021, Dallas-based private equity firm CenterOak rolled up Mullin’s business into a subsidiary called HomeTown Services. The price was undisclosed, but Pitchbook indicates that the sale took place on Dec. 10, 2021—the same day he purchased between $25 million and $50 million of Dreyfus cash management funds.

Mullin told local TV that he retained a roughly 10% stake in the business after selling it. The disclosures aren't perfectly clear—he doesn’t list “Mullin Plumbing” as an asset anymore—but he did acquire between $1 million and $5 million of “COP Hometown Parent LLC,” which in turn controls HomeTown Services, the same day as the sale. A prior employee familiar with Hometown said he wouldn’t be surprised if the value of Mullin’s stake had doubled or tripled in value since the transaction, based on broader trends in the industry. On his most recent disclosure, Mullin’s stake, which may also be shared by his six kids, now falls into the $5 million to $25 million range, indeed indicating an increase in value.

CenterOak, HomeTown and Mullin Plumbing all did not reply to requests for comment.

It was this liquidity event that has helped Mullin, elected to the Senate in 2022, bolster his fortune even more. Today, he boasts a real estate portfolio with at least 46 pieces of commercial, residential and undeveloped property scattered across 13 cities in Oklahoma, plus Versailles, Missouri and Washington, D.C. One home outside Tulsa was purchased in 2022 and, per its Zillow listing, given an over $1 million renovation job before being listed for $2.2 million on March 26. Mullin also still owns Mullin Plumbing’s Tulsa-area headquarters in Broken Arrow, Oklahoma and its Oklahoma City-area Moore office, among other properties associated with the business. He rents the former back to his old company for between $100,000 and $1 million per year and the latter for between $50,000 and $100,000, per his most recent disclosure.

Until recently, Mullin also held a massive array of stocks, bonds and other equities, everything from Adobe to Visa. A New York Times investigation earlier this month found that his trading frequency had increased substantially since he sold his business and that his portfolio had outperformed the market between 2024 and 2026 by 8%. (A Mullin spokesperson told the Times that the senator did not direct his family’s trading.) Mullin agreed to sell off much of his portfolio within 90 days of becoming DHS secretary, shifting into less-conflicted holdings. That move may allow him to defer paying capital gains taxes on those sales until he sells the new assets, thanks to a perk for wealthy people entering the executive branch called certificates of divestiture.

That leaves Mullin with a hodgepodge of other assets. A boat and RV rental company in Checotah, Oklahoma owes one of his companies between $1 and $5 million. He owns stakes in Botanic Tonics, an herbal tonics merchant that sources its leaf kratom from Indonesia and its kava root from Vanuatu; HistoSonics, a healthcare company trying to target liver tumors with sonic beams; and Apres Spectrum, a wastewater treatment venture. Four whole life insurance policies round out his fortune.

In his new role, Mullin will make over $200,000 each year, up from $174,000 when he was a senator. That’s a nice pay bump. Another bonus: Even while DHS remains embroiled in the longest partial government shutdown in U.S. history, as a Senate confirmed-appointee, he’ll be one of the agency employees that will keep collecting paychecks.

© Forbes