A global race for grain trading power is putting more of the world’s vital cereals in the hands of fewer companies, with a string of recent acquisitions raising fears that consumers will pay even more for their food, while farmers are squeezed.

Archer Daniels Midland last week bid for Australia’s last independent grain handler GrainCorp , the latest in a series of moves by grain trading heavyweights to grab a larger slice of a booming market as developing economies seek food security.

The four “ABCD” firms – ADM, Bunge , Cargill and Louis Dreyfus – dominate global grain trading along with top global commodities trader Glencore and Japan’s Marubeni <8002.T>, both of which have made major acquisitions in the last few months.

With food price volatility increasingly coming to the fore, most recently in the wake of drought in the U.S. and other key producing regions, concern is growing among importers about extra upward pressure on prices.