Hamm is chairman of Continental Resources, the biggest oil producer in the Bakken oil basin of North Dakota and Montana. The Oklahoma City-based company also has assets in Wyoming, Oklahoma and Texas. It ended its run as a publicly traded company in November 2022 when Hamm and his family acquired the remaining stock.
The majority of Hamm's fortune is derived from his family's ownership of Continental Resources, an oil and gas producer. Continental is the top leaseholder in the Bakken oil basin in North Dakota and Montana, according to the company's website.
Hamm controls all of the company following the merger of the formerly public company with Hamm's Omega Acquisition in November 2022. He previously held about 83% of the business directly and through family members, according to an October 2022 SEC filing that noted his intention to acquire the company in its entirety.
Continental Resources produced about 450,000 barrels of oil equivalent per day in 2025, according to a November 2025 First Ratings report. Continental's revenue is calculated by multiplying annual production against the 12-month average price of WTI Cushing oil. Continental is then compared to the enterprise value-to-sales multiples of four publicly traded peers: Chord Energy Corp, APA Corp, Northern Oil & Gas Inc and Exxon Mobil Corp.
Earlier filings in 2022 revealed a transfer of shares via a dividend and dissolution agreement from Harold Hamm Family LLC to its members including Hamm's children. Shares held by family members are attributed to Hamm in this analysis to reflect his status as founder and chairman.
Hamm divorced in November 2014 and his wife received more than $1 billion in cash and other assets, such as farm equipment, based on information in the November 2014 Oklahoma divorce decree.
Hamm used to own 61.77% of Hiland Partners, an oil and gas pipeline company he founded, and collected about $1.24 billion when he sold it to Kinder Morgan in February 2015. The value of his cash investments is based on an analysis of these proceeds and expenses, as well as taxes, market performance charitable donations and insider transactions.
Commenting on the transfer of Continental shares in February 2022, Hamm told Bloomberg News: "Full control stays with me, so this changes nothing in that regard."
The youngest of 13 children born to poor Oklahoma sharecroppers, Harold Hamm got into the oil business at age 18, taking over payments on a used tank truck and borrowing $1,000 to create a one-man oilfield services business in rural Ringwood, Oklahoma. Four years later, in 1967, he incorporated Shelly Dean Oil and started wildcatting for oil. Shelly Dean was the start of what is now Continental Resources, one of the largest independent exploration and production oil firms in the US, and the source of Hamm's multi-billion-dollar fortune.
Hamm was quick to recognize the potential of the Bakken oil field in North Dakota. The Bakken, a vast deposit of oil-bearing rock, had been producing oil since the 1950s in relatively small amounts through traditional vertical drilling methods. Hamm was among the first tycoons to utilize horizontal drilling and the fracturing of bedrock to gain access to greater amounts of oil.
He purchased 300,000 acres in the region in 2003. Continental Resources since became the largest leaseholder in the Bakken. Hamm has said that the Bakken field, which stretches into Montana, South Dakota and Canada, will ultimately yield 24 billion barrels.
Hamm completed a deal in 2022 to take the company private.