Jonathan Mariner
General Partner, Chief Financial Officer
Jonathan Mariner is a seasoned business executive, investor, and technology entrepreneur, currently serving as a Managing Partner at Harbinger Alternative Associates, LLC, where he helps lead investment strategies focused on innovation across the sports, media, and entertainment landscape. With a distinguished track record in finance, operations, and digital transformation, Mariner brings deep institutional and entrepreneurial insight to the fund’s portfolio strategy.
Executive Leadership in Sports & Finance
Mariner spent over a decade at Major League Baseball (MLB), where he served as Chief Financial Officer before becoming the league’s first-ever Chief Investment Officer. As CFO, he oversaw the financial operations of all 30 clubs, driving fiscal discipline, revenue growth, and large-scale strategic initiatives. He was later tapped to lead MLB’s investment strategy, managing the league’s private equity interests and evaluating opportunities across emerging tech, media, and fan engagement platforms.
Before joining MLB, Mariner held senior financial roles at several MLB clubs, including the Florida Marlins and the Florida Panthers. He also served as Vice President and CFO of the Beacon Council, Miami-Dade County’s economic development agency.
Entrepreneurship & Innovation
After his tenure in professional sports, Mariner founded TaxDay, a private software firm that operates a mobile app to help track multi-state travel for tax residency. He was previously appointed by The Walt Disney Company as the Interim Head of Regional Sports Networks for the Fox Regional Sports Networks (RSNs), overseeing all programming, distribution, sales, and operational functions until sale to Sinclair Broadcasting.
Mariner is also a sought-after advisor and board member, including currently serving as a Senior Advisor in the Sports Advisory practice for Andalusian Pricate Capital. He currently serves on the boards of Rocket Mortgage; Five9, Inc.; IEX; Delaware North, Inc., and Overtime Sports, Inc. His volunteer work included serving on the board of Little League Intl; the Board of Trustees of the UVA Darden School of Business; and the Knight Commission on Intercollegiate Athletics.
Education & Personal Life
Mariner holds an MBA from Harvard Business School, a bachelor’s degree in accounting from the University of Virginia, and he is a former Certified Public Accountant. A strong advocate for diversity and mentorship in business, he supports programs that expand access to opportunities in sports, finance, and entrepreneurship.
He resides in both Charlottesville and Florida, and he enjoys mentoring young entrepreneurs, exploring new technologies, and spending time with his family.
Our Team
The Harbinger team brings an unprecedented assembly of sports ownership experience, operational expertise, and financial innovation
Jonathan Mariner
General Partner, Chief Financial Officer
Jonathan Mariner is a seasoned business executive, investor, and technology entrepreneur, currently serving as a Managing Partner at Harbinger Alternative Associates, LLC, where he helps lead investment strategies focused on innovation across the sports, media, and entertainment landscape. With a distinguished track record in finance, operations, and digital transformation, Mariner brings deep institutional and entrepreneurial insight to the fund’s portfolio strategy.
Executive Leadership in Sports & Finance
Mariner spent over a decade at Major League Baseball (MLB), where he served as Chief Financial Officer before becoming the league’s first-ever Chief Investment Officer. As CFO, he oversaw the financial operations of all 30 clubs, driving fiscal discipline, revenue growth, and large-scale strategic initiatives. He was later tapped to lead MLB’s investment strategy, managing the league’s private equity interests and evaluating opportunities across emerging tech, media, and fan engagement platforms.
Before joining MLB, Mariner held senior financial roles at several MLB clubs, including the Florida Marlins and the Florida Panthers. He also served as Vice President and CFO of the Beacon Council, Miami-Dade County’s economic development agency.
Entrepreneurship & Innovation
After his tenure in professional sports, Mariner founded TaxDay, a private software firm that operates a mobile app to help track multi-state travel for tax residency. He was previously appointed by The Walt Disney Company as the Interim Head of Regional Sports Networks for the Fox Regional Sports Networks (RSNs), overseeing all programming, distribution, sales, and operational functions until sale to Sinclair Broadcasting.
Mariner is also a sought-after advisor and board member, including currently serving as a Senior Advisor in the Sports Advisory practice for Andalusian Pricate Capital. He currently serves on the boards of Rocket Mortgage; Five9, Inc.; IEX; Delaware North, Inc., and Overtime Sports, Inc. His volunteer work included serving on the board of Little League Intl; the Board of Trustees of the UVA Darden School of Business; and the Knight Commission on Intercollegiate Athletics.
Education & Personal Life
Mariner holds an MBA from Harvard Business School, a bachelor’s degree in accounting from the University of Virginia, and he is a former Certified Public Accountant. A strong advocate for diversity and mentorship in business, he supports programs that expand access to opportunities in sports, finance, and entrepreneurship.
He resides in both Charlottesville and Florida, and he enjoys mentoring young entrepreneurs, exploring new technologies, and spending time with his family.
Jonathan Mariner
General Partner, Chief Financial Officer
Jonathan Mariner is a seasoned business executive, investor, and technology entrepreneur, currently serving as a Managing Partner at Harbinger Alternative Associates, LLC, where he helps lead investment strategies focused on innovation across the sports, media, and entertainment landscape. With a distinguished track record in finance, operations, and digital transformation, Mariner brings deep institutional and entrepreneurial insight to the fund’s portfolio strategy.
Executive Leadership in Sports & Finance
Mariner spent over a decade at Major League Baseball (MLB), where he served as Chief Financial Officer before becoming the league’s first-ever Chief Investment Officer. As CFO, he oversaw the financial operations of all 30 clubs, driving fiscal discipline, revenue growth, and large-scale strategic initiatives. He was later tapped to lead MLB’s investment strategy, managing the league’s private equity interests and evaluating opportunities across emerging tech, media, and fan engagement platforms.
Before joining MLB, Mariner held senior financial roles at several MLB clubs, including the Florida Marlins and the Florida Panthers. He also served as Vice President and CFO of the Beacon Council, Miami-Dade County’s economic development agency.
Entrepreneurship & Innovation
After his tenure in professional sports, Mariner founded TaxDay, a private software firm that operates a mobile app to help track multi-state travel for tax residency. He was previously appointed by The Walt Disney Company as the Interim Head of Regional Sports Networks for the Fox Regional Sports Networks (RSNs), overseeing all programming, distribution, sales, and operational functions until sale to Sinclair Broadcasting.
Mariner is also a sought-after advisor and board member, including currently serving as a Senior Advisor in the Sports Advisory practice for Andalusian Pricate Capital. He currently serves on the boards of Rocket Mortgage; Five9, Inc.; IEX; Delaware North, Inc., and Overtime Sports, Inc. His volunteer work included serving on the board of Little League Intl; the Board of Trustees of the UVA Darden School of Business; and the Knight Commission on Intercollegiate Athletics.
Education & Personal Life
Mariner holds an MBA from Harvard Business School, a bachelor’s degree in accounting from the University of Virginia, and he is a former Certified Public Accountant. A strong advocate for diversity and mentorship in business, he supports programs that expand access to opportunities in sports, finance, and entrepreneurship.
He resides in both Charlottesville and Florida, and he enjoys mentoring young entrepreneurs, exploring new technologies, and spending time with his family.
Jonathan Mariner is a seasoned business executive, investor, and technology entrepreneur, currently serving as a Managing Partner at Harbinger Alternative Associates, LLC, where he helps lead investment strategies focused on innovation across the sports, media, and entertainment landscape. With a distinguished track record in finance, operations, and digital transformation, Mariner brings deep institutional and entrepreneurial insight to the fund’s portfolio strategy.
Executive Leadership in Sports & Finance
Mariner spent over a decade at Major League Baseball (MLB), where he served as Chief Financial Officer before becoming the league’s first-ever Chief Investment Officer. As CFO, he oversaw the financial operations of all 30 clubs, driving fiscal discipline, revenue growth, and large-scale strategic initiatives. He was later tapped to lead MLB’s investment strategy, managing the league’s private equity interests and evaluating opportunities across emerging tech, media, and fan engagement platforms.
Before joining MLB, Mariner held senior financial roles at several MLB clubs, including the Florida Marlins and the Florida Panthers. He also served as Vice President and CFO of the Beacon Council, Miami-Dade County’s economic development agency.
Entrepreneurship & Innovation
After his tenure in professional sports, Mariner founded TaxDay, a private software firm that operates a mobile app to help track multi-state travel for tax residency. He was previously appointed by The Walt Disney Company as the Interim Head of Regional Sports Networks for the Fox Regional Sports Networks (RSNs), overseeing all programming, distribution, sales, and operational functions until sale to Sinclair Broadcasting.
Mariner is also a sought-after advisor and board member, including currently serving as a Senior Advisor in the Sports Advisory practice for Andalusian Pricate Capital. He currently serves on the boards of Rocket Mortgage; Five9, Inc.; IEX; Delaware North, Inc., and Overtime Sports, Inc. His volunteer work included serving on the board of Little League Intl; the Board of Trustees of the UVA Darden School of Business; and the Knight Commission on Intercollegiate Athletics.
Education & Personal Life
Mariner holds an MBA from Harvard Business School, a bachelor’s degree in accounting from the University of Virginia, and he is a former Certified Public Accountant. A strong advocate for diversity and mentorship in business, he supports programs that expand access to opportunities in sports, finance, and entrepreneurship.
He resides in both Charlottesville and Florida, and he enjoys mentoring young entrepreneurs, exploring new technologies, and spending time with his family.
Jonathan Mariner
General Partner, Chief Financial Officer
Jonathan Mariner is a seasoned business executive, investor, and technology entrepreneur, currently serving as a Managing Partner at Harbinger Alternative Associates, LLC, where he helps lead investment strategies focused on innovation across the sports, media, and entertainment landscape. With a distinguished track record in finance, operations, and digital transformation, Mariner brings deep institutional and entrepreneurial insight to the fund’s portfolio strategy.
Executive Leadership in Sports & Finance
Mariner spent over a decade at Major League Baseball (MLB), where he served as Chief Financial Officer before becoming the league’s first-ever Chief Investment Officer. As CFO, he oversaw the financial operations of all 30 clubs, driving fiscal discipline, revenue growth, and large-scale strategic initiatives. He was later tapped to lead MLB’s investment strategy, managing the league’s private equity interests and evaluating opportunities across emerging tech, media, and fan engagement platforms.
Before joining MLB, Mariner held senior financial roles at several MLB clubs, including the Florida Marlins and the Florida Panthers. He also served as Vice President and CFO of the Beacon Council, Miami-Dade County’s economic development agency.
Entrepreneurship & Innovation
After his tenure in professional sports, Mariner founded TaxDay, a private software firm that operates a mobile app to help track multi-state travel for tax residency. He was previously appointed by The Walt Disney Company as the Interim Head of Regional Sports Networks for the Fox Regional Sports Networks (RSNs), overseeing all programming, distribution, sales, and operational functions until sale to Sinclair Broadcasting.
Mariner is also a sought-after advisor and board member, including currently serving as a Senior Advisor in the Sports Advisory practice for Andalusian Pricate Capital. He currently serves on the boards of Rocket Mortgage; Five9, Inc.; IEX; Delaware North, Inc., and Overtime Sports, Inc. His volunteer work included serving on the board of Little League Intl; the Board of Trustees of the UVA Darden School of Business; and the Knight Commission on Intercollegiate Athletics.
Education & Personal Life
Mariner holds an MBA from Harvard Business School, a bachelor’s degree in accounting from the University of Virginia, and he is a former Certified Public Accountant. A strong advocate for diversity and mentorship in business, he supports programs that expand access to opportunities in sports, finance, and entrepreneurship.
He resides in both Charlottesville and Florida, and he enjoys mentoring young entrepreneurs, exploring new technologies, and spending time with his family.