His exit follows the recent departure of Rob Reilly, managing director and co-head of fixed income and currencies, Asia Pacific, and Andrew Wardle, managing director and head of global markets.
At SocGen, Dimmock reported to Yann Garnier, head of sales for fixed income and cross asset solutions, Asia Pacific.
Prior to joining SocGen in 2010, Dimmock was head of institutional fx sales at Bank of America-Merrill Lynch in London.
Dimmock could not be reached and Garnier did not return calls. A SocGen spokeswoman declined to comment.