Yellow says shareholders will receive about 65 percent cash and 35 percent Yellow Roadway stock under the revised offer. Originally, the transaction was structured as about 50 percent cash and 50 percent stock.
Yellow Roadway chairman Bill Zollars calls the decision "a mutually beneficial change."
USF shareholders are still expected to vote on the deal May 23, with a closing anticipated one day later.
Both freight companies have terminals in Rockford near the airport.