The United States Anti-Doping Agency (USADA) has announced four fighters have tested positive for the performance-enhancing drug (PED) Ostarine. The positive samples came from out-of-competition tests.

ESPN’s Ariel Helwani reported today that the four fighters who tested positive include Sean O’Malley, Nicco Montaño, Augusto Mendes, and Marvin Vettori. All four were subsequently handed six-month suspensions. O’Malley’s suspension is already up, while Montano’s is up next month:

“USADA just announced that Sean O’Malley, Nicco Montaño, Augusto Mendes & Marvin Vettori all tested positive for the PED ostarine in recent out-of-competition drug tests & were subsequently suspended six months. O’Malley’s suspension is already up while Montaño’s is up next month.”

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The 24-year-old O’Malley is currently undefeated in his mixed martial arts (MMA) career. His last Octagon appearance resulted in a unanimous decision victory over Andre Soukhamthath at UFC 22 last March. As for Montano, the former UFC women’s flyweight champion won the inaugural title in her last outing by outlasting Roxanne Modafferi.

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Mendes hasn’t been active since being defeated by Aljamain Sterling in April of last year. Finally, Vettori hasn’t fought since his split decision loss to Israel Adesanya, also in April of last year.