The Teamsters union on Tuesday called on the U.S. Senate to investigate Yellow's bankruptcy as part of a broader investigation the lawmaking body's judiciary committee is conducting on "corporate manipulation of Chapter 11 bankruptcy."

Chapter 11 filings are more and more being used as a path to liquidate assets instead of attempting to restructure operations and outstanding obligations.

"Yellow is trying to fast track liquidation," said Fred Zuckerman, Teamsters general secretary-treasurer, in a statement. "We haven't had bankruptcy reform in this country for nearly two decades. We need to take this opportunity to right the wrongs at Yellow and prevent them from happening again."