The advertising inventory is sold out, according to Seth Winter, Fox’s head of sports sales, and that includes a fourth “nightcap” game that airs at 9 p.m. New York time on the company’s Fox Sports 1 cable channel.

“Our baseball inventory 10 days ago just shot off the shelf when people realized that we could put a product on the field,” Winter said in an interview.

The spread of the Covid-19 virus and the suspension of live sports in March jarred the ad market and prompted a lot of dire predictions. But advertisers’ response to the return of games is proving to be its own surprise, according to Winter.

In the past, baseball ad spending would be spread out over months, with as little as 60% of the inventory snapped up at the beginning of the season. As of now, 90% of the virus-shortened regular season is sold, according to Winter.

“We just had a tsunami of investment,” he said.

Baseball, which returns Thursday night with a 60-game season, could benefit from the pent-up demand of sports fans who have been stuck at home with little to do but watch TV. Other returning sports, including Nascar and Major League Soccer, have seen an initial bump in audiences.

Audience ratings for eight preseason baseball games aired on regional sports networks last weekend were more than double those of spring-training games played earlier in the year, according to Home Team Sports, a Fox division that sells ads on those networks. Some seats in the empty stadiums were filled with cardboard cutouts of fans paid for by baseball lovers.

The national baseball advertising market amounted to $584 million last year, according to Kantar Media. Fox is the largest player thanks to a lineup that includes a league championship and the World Series.

Sticking Around

The network convinced most of its sponsors to stick with their spending plans after sports went on hiatus. A few advertisers that asked for their money back have returned, Winter said. Newcomers are paying about 10% more than they would have had they bought in earlier.

The network is seeing higher spending by technology companies, including makers of products for kids who will be attending school online in the fall. Spending by mortgage companies is also up, as Americans take advantage of low interest rates.

Because of the shortened season, fans will get to see more games at convenient local times and more classic rivalries, like the New York Yankees and Boston Red Sox, according to Michael Mulvihill, head of strategy at Fox Sports.

Still, the broadcaster had to adjust its programming lineup. Last month, the company sold its U.S. Golf Association broadcast rights at a loss to Comcast Corp.’s NBC, in part because rescheduled tournaments bumped up against football in the fall.

Football, a huge business for Fox, remains a problem. The National Football League might cancel its preseason games, and whether college matchups return is still up in the air. Some collegiate conferences have already canceled games.

“We know we’re going to have football, we know we’re going to have a season — what that looks like remains to be seen,” Winter said. “I expect football to be sold out regardless of the breadth and scope of the season.”

Not everyone is convinced the return of sports will be a home run.

Audiences may not want a full day of sports, preferring instead to spend time outside in the summer, according to Raghu Kodige, chief product officer of Alphonso, a media research firm. Fans may also not take shortened seasons seriously.

“These will not be ‘normal’ baseball and basketball seasons,” he said.