Senators Elizabeth Warren (D-MA) and Senator Mike Rounds (R-SD) have introduced a resolution directing the Federal Trade Commission to determine whether price fixing by beef companies has occurred and to report back to Congress within a year.
Apparently, Senator Warren is fixated over the fact that four major companies (Cargill, Tyson Foods, JBS US and National Beef Packing Company) are responsible for processing 85% of cattle. 
Concentration may not necessarily represent the potential for collusion especially in a competitive market but it does ensure efficiency and consistency in supply.
Countering the prevailing and politically inspired animus against "Big Beef" Donnie King, president of Tyson Foods noted that the “Purchase of cattle from ranchers and feed lots is based on supply and demand and that commercial pressures and availability in relation to demand sets retail prices”.