So much for the run on cheap gold mines. Producers who were forced by slumping prices to unload assets last year are regaining leverage.

With bullion off to its biggest rally to start a year in four decades aided by the U.K.’s vote to quit the EU mine buyers are paying higher premiums and the pace of deals is accelerating, data compiled by Bloomberg show. The value of reserves held by major producers has almost doubled since the third quarter of last year, according to Bloomberg Intelligence.