Advertisers kept a tighter grip on their wallets when it came to the NFL this season.

Revenue on game-time commercials slid 1.2 percent during the 2017 regular season, to $2.42 billion, from a year ago, according to data from Standard Media Index, which has studied advertiser spending on NFL telecasts for the past four seasons.

The 2017 season was the first time advertisers spent less on NFL telecasts, SMI said.

In 2015, revenue rose 9.6 percent, to $2.38 billion, from $2.17 billion in 2014. In 2016, ad revenue rose 2.9 percent, to $2.45 billion.

“For the first time since we have been tracking the market, we saw a slight drop of in-game dollars,” James Fennessy, chief executive of SMI, said in a statement.

Despite the 2017 decline, companies were still paying top dollar to advertise, he said.

The cost of a 30-second NFL spot rose 1.2 percent, to $505,000. However, because of a 9.7 percent ratings decline, the number of make-good ads — those supplied by the networks to make up for the shortfall in viewers — grew 23 percent, up from 21 percent.

The NFL received 5.4 percent fewer dollars from carmakers, the No. 1 ad category, SMI said.

Consumer electronics, the No. 2 ad category, saw ad dollars slide 3 percent.

Insurance, alcoholic beverages and quick-serve restaurants increased NFL ad spend with respective gains of 30 percent, 16 percent and 6.4 percent.

Despite the dips, however, major media companies continue to line up for the game.

In December, Verizon ponied up more than $2 billion over five years in a new NFL streaming deal, including the Super Bowl, to all smartphone users, not just Verizon customers.