Macy's 2015 holiday window display at Macy's in Herald Square.

U.S. brand management company Iconix Brand Group is exploring a sale of its majority stake in Peanuts Worldwide, which owns the rights to cartoon strip characters Snoopy and Charlie Brown, according to people familiar with the matter.

The move comes three months after U.S. insurance company MetLife dropped the Peanuts characters it had been using as mascots for more than 30 years — a blow to debt-burdened Iconix.