Delta Air Lines and its merger partner, Northwest Airlines, on Wednesday joined the list of US carriers to report quarterly losses amid record fuel costs.

An unrelenting surge in oil prices, which have neared $120 a barrel, has wiped out profits and pressed carriers to scramble for ways to trim additional costs, from shrinking their flight schedules and retiring less fuel-efficient aircraft to job cuts. Investors’ concerns for the industry’s future peaked on Tuesday, when United Airlines’ wider-than-expected loss touched off steep declines on US airlines’ stocks.