Forst was born in Santa Monica, California, and raised in Encino, California.[1][2] He attended Brentwood School in Brentwood, Los Angeles.[3] Forst's wife is Rebe Glass, a lawyer with the San Francisco law firm Cooley Godward Kronish.[4] Glass and Forst met at Harvard, where Glass was captain of the soccer team and a member of the 1997 All-Ivy Team, Second Team.[4][5] They have a son (Judah) and a daughter (Sasha), and live in Berkeley, California, as well as a niece (Serena), and a nephew (Ryan) who live near them in Burlingame. [6]
In 2000, Forst sent his résumé to MLB teams and was hired by the Oakland Athletics as a scout.[12][14] He became the Athletics' assistant general manager in 2004, succeeding Paul DePodesta.[10] He turned down opportunities to interview for the general manager position with the Seattle Mariners and San Diego Padres.[11][15] After the 2015 season, the Athletics announced that, with Billy Beane being promoted to executive vice president of baseball operations, Forst would be promoted to general manager.[16]
Note: Those listed here have final authority in personnel decisions for their team, typically holding a title of President of Baseball Operations, Executive Vice President of Baseball Operations, Chief Baseball Officer, and/or General Manager.