The Wyoming Permanent Mineral Trust Fund (WPMTF) is a sovereign wealth fund of the U.S. state of Wyoming. Established in 1975 by constitutional amendment, it is funded by a 1.5 percent severance tax on "coal, petroleum, natural gas, oil shale, and such other minerals". The fund is managed by the Wyoming State Treasurer. In 2025, the fund has a reported market value of over $12 billion.
Each year, 5 percent of the WPMTF's average annual market value from the previous five years can be spent through the Wyoming General Fund.
During the 1889 Wyoming Constitutional Convention, severance taxes on natural resources were discussed by delegates, but were not adopted. In 1924, a proposed constitutional amendment on implementing a severance tax was narrowly defeated. A 1974 constitutional amendment passed with 78,842 votes in favor of the constitutional amendment and 32,414 against.
With a reported value of $12,371,201,462 as of October 2025, the WPMTF constituted the largest single fund in the state's investment portfolio, accounting for 37% of the state portfolio's total market value. Other funds in the portfolio include the Permanent Land Funds and the Workers Compensation Fund.
All investment income from the WPMTF is constitutionally required to be transferred annually to the Wyoming General Fund. In 2004, Wyoming Statute ç 9-4-719 established a spending cap, the Spending Policy Amount, on the WPMTF's investment earnings of 5 percent of the fund's prior five-year average market value, with the any amounts greater than that being returned by the general fund to the WPMTF Reserve Account.
A 2012 WyoFile analysis found that the WPMTF accounted for an average of 18.6% of general fund revenue between 1987 and 2011. In the Wyoming 2023-2024 budget, the WPMTF provided $525.8 million in revenue.
In 2014, state senator Charles Scott (R-Casper), called the WPMTF, "Perhaps the smartest financial move the people of Wyoming have ever made," arguing that "the income from the fund is available to help the state meet its essential obligations when economic times are tough, reducing the need to raise taxes." In an interview with Wyoming Public Radio, then-State Treasurer Mark Gordon, praised the WPMTF as a "significant revenue generator for the state."
Others have questioned the fund's role in Wyoming's budgeting practices. Writer and lecturer Samuel Western called the fund a "mixed blessing" in 2012, suggesting that the WPMTF has "kept Wyoming complacent in its quest for economic diversification" A 2022 article in the California Journal of Politics and Policy by Robert A. Schuhmann and Jeffrey Jensen of the University of Wyoming observed, "There seems little incentive to diversify the [Wyoming] tax structure with the relatively high percentage of interest from the WPMTF used for the General Fund."