In a call market, the price is set by the exchange so the market will clear, or almost clear, every time orders are filled. This is in stark contrast to the auction market, where prices are determined by buyers and sellers.
Because the call market groups transactions together, there is a substantial increase in liquidity. Although liquidity is generally considered to be a good quality in any marketplace, sellers may lose some of the liquidity premium, which is can be substantial.
Investment dictionary. Academic. 2012.