Veteran MBS analyst Evan Firestone has leftMerrill Lynch the firm. Firestone, who had been an MBS analyst for over 17 years, making him one of the Street's longest serving veterans, told the firm he wanted to take time off and possibly do something in the film industry, a field in which he holds a graduate degree. His boss, mortgage research head and U.S. fixed income strategist Ken Hackel, says the parting was amicable and the firm is currently debating whether to hire a replacement or shift someone over to his slot internally. Prior to joining Merrill, Firestone was at Greenwich Capital Markets and First Boston. Calls to Firestone's home were not returned as of press time.