Stephen Gibson resigned as president of Liberty Advisers on Friday. The resignation comes less than a month after Fleet Asset Management closed a deal to purchase Liberty. Mr. Gibsons departure coincides with the reorganization of Liberty funds into Fleet, said Wendy Rauch, Liberty spokeswoman. Mr. Gibson, who joined Liberty in 1996 as head of the firms retail mutual fund activities, plans to pursue an unannounced entrepreneurial venture, according to Ms. Rauch. Mr. Gibson could not be reached for comment.