The announcement this week marked the first fare hikes of the year and, as of Friday afternoon, had been matched by Delta, with American and US Airways taking a "minimal matching" approach, Rich Seaney of FareCompare.com told the Chicago Tribune.
The United action, coupled with Star Alliance member Air Canada, took effect Thursday and affected 1 million fares.
Seaney told the Tribune that only seven of 15 attempted air fare increases last year were successful.
Notable deaths of 2014 [PHOTOS]
Larry Ellison to step down as CEO of Oracle