The Mayfair Fund is the hedge fund used by the L.A. Dollhouse to receive payment from a client seeking to procure the services of an Active. The Mayfair Fund has been in use for an unspecified number of years, and can be accessed by Federal Agents working for the FBI.
Gabriel Crestejo made a payment to the Mayfair Fund when procuring Echo's services to negotiate, and ultimately rescue, his daughter Davina Crestejo. (S1: "Man on the Street") Paul Ballard's discovery of this drew the ire of Graham Tanaka, as the kidnapping and rescue of Davina had been his case, which he since closed. (S1: "The Target", "Man on the Street")
Joel Mynor made a payment on the same date every year that he hired an active to be imprinted with the personality of his deceased wife, Rebecca Mynor so that he could see the look on her face when he presented their new home. (S1: "Man on the Street")