While the new year has just begun and most people are either in the middle of traveling home or have just returned, Delta Airlines has launched the first airfare hike of 2016, according to the Los Angeles Times.

The increase will be up by $4 per flight and was first initiated as of Monday morning. This increase was matched, a few hours later, by Southwest Airlines and then the increase was matched by American and United Airlines as of Tuesday morning. Fare hikes have usually been matched by most of the major carriers once Southwest has gone along with an increase.

According to the Los Angeles Times, “Rick Seaney, founder of the travel site Farecompare.com, said the increase was surprising, considering that nearly every major carrier has been collecting record profits recently because of low fuel costs. ‘What the airlines are doing is what they’ve always done: probing consumers’ appetite for travel by determining their pain-point on price,’ he said on his website.”

The latest data reported by the U.S. Department of Transportation shows that the nation’s 10 largest commercial carriers have a net profit of $9.3 billion in the third quarter of 2015, which went up from $3.1 billion in the third quarter of 2014.

The increase will be added to almost every type of flight including short, medium and long-haul flights.