24 Hour Fitness is the world's largest (by memberships) privately owned and operated fitness center chain, and third in number of clubs behind Gold's Gym and Fitness First of the UK. It currently has 400+ clubs, 18,000 employees in the United States, and an undisclosed number of employees working in a customer services call-center in the Philippines and another call center in Las Vegas, Nevada. 24 Hour Fitness also employs a collections contracting company located in Jamaica. The corporate office is located in San Ramon, California and a processing center is located in Carlsbad, California. The founder is Mark S. Mastrov, and the CEO is Mark Smith. 24 Hour Fitness is currently owned by AEA Investors, a leader in the private equity industry; Ontario Teachers’ Pension Plan, Canada's largest