A private-equity firm founded and managed by John Stewart, the head of newly prominent Thoroughbred owner Resolute Racing, has been sued along with other founders of the company by an anchor investor that provided funds for Stewart’s company to manage.

The suit, filed by Archean Capital Partners against MiddleGround Management and three principals including Stewart, was filed Dec. 19. The case was sealed until Jan. 9, when a judge ruled that it should be made public. The lawsuit previously was reported by T. D. Thornton of Thoroughbred Daily News.

Stewart is best known in horse-racing circles for launching Resolute Racing. Since starting in 2023, Resolute has purchased Shadwell’s former Shadayid Stud, which is now Resolute Farm. They have acquired a high-profile broodmare band including Puca, the dam of Kentucky Derby winner Mage and Belmont winner Dornoch; Forte’s dam Queen Caroline; and Breeders’ Cup winners Caravel, Goodnight Olive and Pizza Bianca. They also campaign horses, mainly in partnership, including Grade 1 winner Didia and Grade 1-placed Kentucky Derby starter Just a Touch. Resolute Racing also is the title sponsor of the 2025 Eclipse Awards.

MiddleGround and its partners have been accused by Archean Capital Partners of acting in “bad faith” for not paying a share of the company’s revenue, using that money for their businesses or personal obligations, and that the company or its principals “acquired other businesses without first obtaining Archean’s contractually required consent.” Archean alleges that they are due more than $22 million under the investment contract.

Archean does not allege that Stewart used its funds to operate Resolute Racing. However, the agreement at the center of the lawsuit outlined that MiddleGround’s principals were supposed to “devote the substantial majority” of the time they spent working on managing the fund in question. Instead, Archean alleges that the time Stewart has spent in the Thoroughbred industry has detracted from the time he spent managing the fund, making it less than the time promised in the agreement without giving them notice that he would be spending less than that share of his working time. They also allege that they were entitled to notice of his racing investments under the contract, under the term that they were supposed to be notified if a MiddleGround principal acquired another business.

In response, Stewart posted a statement Thursday evening on X. Though the statement does not mention Archean by name, it mentions MiddleGround Capital as his “primary focus” in his professional life. According to the statement, MiddleGround “faced a disagreement with an organization we believed was attempting to leverage litigation to pressure us into an unfair agreement,” but did not provide further details about the litigation, citing advice of legal counsel.