Sunday's Valencia MotoGP season finale also marked the last event for San Carlo as title sponsor of the Gresini team.
San Carlo has backed Gresini for the last seven years, and been its MotoGP title sponsor since 2008. This year they were also main sponsor for the new Moto3 team.
“This is an announcement we have to make with a heavy heart because over these years together with San Carlo we have built an important project which has created fantastic moments and also been subject to great tragedy due to the death of Marco [Simoncelli],” said team principal Fausto Gresini.
“The extraordinary backing and energy of San Carlo President Alberto Vitaloni has provided the backbone of a project I will be eternally proud to have put together. My heartfelt thanks go to Alberto Vitaloni for making this incredible experience possible.”
Vitaloni added: “We have been part of a project that has created moments of great joy and others of deep sadness. To lose a person like Marco, who was always more of a friend to us than a rider, brought great suffering.
“I would like to thank Fausto and all his staff. It was a pleasure and an honour to work with you and our time together will always be one of my greatest memories.”
Alvaro Bautista, who finished fifth in this year's championship with two podiums and one pole position, has signed to continue on Gresini's Honda RC213V for 2013.
However Michele Pirro, who rode the team's FTR-Honda and claimed a new CRT best of fifth place on Sunday, is switching to the role of Ducati test rider.
The Italian's replacement is yet to be announced.