Jonathan Mariner A's Part-Owner

     One-time South Florida sports executive Jonathan Mariner is the new part-owner of the Athletics baseball franchise. His organization Harbinger Sports Ventures, which launched in May 2025, along with Mark Cuban bought a minority share of the Athletics. The A's are expected to start playing in Las Vegas beginning in 2028. 

     Mariner worked under local sports owner H. Wayne Huizenga during the 1990s. He was the chief financial officer of the Florida Marlins beginning in February 1992 and later added duties as an executive vice president. 

     He also was the executive vice president and chief financial officer of the Florida Panthers when Huizenga was awarded a NHL franchise by the National Hockey League at The Breakers Hotel in Palm Beach in December 1992. Mariner held the post until just before the start of their inaugural season in September 1993. 

     Mariner joined Major League Baseball in March 2002 and was the executive vice president and chief financial officer for almost 13 years. He was elevated to chief investment officer by new MLB commissioner Rob Manfred in January 2015 and held that role until Mariner retired in May 2016.