Shortly after graduating from Northwestern University and starting his career as a coffee boy for Tom Hanks on the Gary Marshall-directed NOTHING IN COMMON and working as a production assistant on HANOI HILTON starring Michael Moriarty, David Soul and Jeffrey Jones, Posner went to work for world-renowned filmmaker Pedro Almodovar, playing a key role in the financing, distribution, marketing and PR for his early films, including his breakthrough Academy Award-nominated WOMEN ON THE VERGE OF A NERVOUS BREAKDOWN. He went on to produce Almodovar’s Golden Globe nominee HIGH HEELS and TIE ME UP, TIE ME DOWN starring Antonio Banderas. In 1992, Posner created his own production company and film production fund, Filmania. He produced several films, including UNCOVERED, directed by Jim McBride and starring Kate Beckinsale; LOST IN TRANSIT, starring Jean Rochefort; STIFF UPPER LIPS, starring Sir Peter Ustinov and METROLAND starring Christian Bale. He also helped structure financing for several films including Roman Polanski’s DEATH AND THE MAIDEN and Sally Potter’s TANGO LESSON.

In 2001, Posner became a studio executive and served as Managing Director of Warner Bros Pictures Int´l Spain. During that time he was responsible for theatrical distribution and marketing in Spain of over 130 WB films including the first 3 installments of HARRY POTTER, THE MATRIX sequels, the Tom Cruise vehicle THE LAST SAMURAI  and Keanu Reeves’ CONSTANTINE amongst many others.  Posner helped launch WB’s local production division and served as a local Executive liaison on Guillermo del Toro’s Academy Award-nominated PAN’S LABYRINTH and Milos Forman’s GOYA’S GHOSTS starring Natalie Portman and Javier Bardem.

In 2007, he co-founded an international Film sales company, 6 Sales, which has handled foreign sales on over 50 films including Sally Potter’s RAGE starring Jude Law and early works from director Alfonso Cuaron. In 2009 Posner sold that company and joined forces with Antonio Banderas and 3D animated studio Kandor Graphics. Together they produced 3 animated features; THE MISSING LYNX, JUSTIN, THE KNIGHTS OF VALOR starring Saoirse Ronan, Freddy Highmore and Julie Walters; and the short film, THE LADY AND THE REAPER which received an Academy Award nomination in 2009 for Best Animated Short Film. 

In 2014 Posner and Paco Arango formed a venture in to jointly produce films directed by Arango, including THE HEALER starring Oliver Jackson-Cohen, Camilla Luddington, Jorge Garcia and Jonathan Pryce.