Delta Air Lines on Monday slashed its first-quarter profit estimates by half, sending its shares down 14%, and its CEO said the environment had weakened due to U.S. economic uncertainty.

Delta Air Lines Inc. cut its profit expectations for the first quarter roughly by half on weakening travel demand, the latest sign that economic worries are pressuring consumer spending.

Economic malaise among consumers and businesses is softening domestic travel demand, prompting the Atlanta-based airline to set its year-over-year revenue growth forecast for the first quarter at 3-4%, down from initial guidance of 7-9%, according to a Monday filing with the U.S. Securities and Exchange Commission.