Ali Krieger knew all too well the frustration her family and friends felt when they couldn’t find her jerseys, be it the U.S. national team or her NWSL club version.

Back in 2016, Krieger was looking for a Sue Bird jersey. Seattle Storm, Team USA — she didn’t much care. She just wanted the jersey of her friend, who was the most prominent, and popular, U.S. women’s basketball player at the time.

Most sporting goods stores didn’t carry them, however, in store or online. When Krieger did find sites that had Bird’s jersey, they were either sold out or not available in her size.

“I searched way too long for a Sue Bird jersey,” the two-time World Cup champion said. “Finally I said, `I’m going to reach out to her and see if she can point me in the right direction.’ But not everyone has that luxury.”

The lack of merchandise options, or lack of merchandise period, isn’t just a source of annoyance to women’s sports fans. It’s one more example of the economic inequities that have held women’s sports back. And it's costing the companies that make and sell merch, as well as teams and leagues. As much as $4 billion a year, according to a new data analysis by Klarna and the Sports Innovation Lab released Wednesday.

That’s right, $4 billion. With a B.

“There's a big market here and, like everything else in women's sports, it has been underserved, misunderstood and there's things we can do to fix it very easily,” Angela Ruggiero, the Hall of Fame ice hockey player who is co-founder of Sports Innovation Lab, told USA TODAY Sports.

“You’re a walking billboard when you have a jersey on. That is free marketing,” Ruggiero added. “So you’re only leaving money on the table.”

For decades, women’s sports have been treated more like charity projects than potential money makers. There’s been minimal investment and equally insignificant exposure. Three years ago, however, Sports Innovation Lab began its “Fan Project,” designed to poke holes in the notion there’s no market for women’s sports and to illustrate the different ways companies and leagues are short-changing themselves as a result.

The new study, titled Rep Her: Revealing the Unmet Demand for Women’s Sports Merchandise, looked at merchandise by using surveys of fans and Klarna purchasing trends, as well as analysis of transaction data, products in stores and Google trends. In addition to calculating the value of the largely untapped market, the study found:

• 60% of women’s sports fans have wanted to buy merchandise but couldn’t because of a lack of inventory
• 79% of fans said they would buy more women’s sports merchandise if it was available
• For every nine pieces of merchandise for men’s sports, there’s one for women’s sports
• There is a particularly glaring disparity in hats, with 66 times more NBA options than WNBA offerings
• 67% have bought women’s sports merch without attending a live sporting event

“We all knew, because of the sold-out inventory, that there was more demand than supply. But the just how much — that 60% went to buy and couldn't, I just felt was astronomical. I can't think of another industry that wouldn't resolve that immediately,” said Gina Waldhorn, Sports Innovation Lab’s chief marketing officer.

“Yes, they want styles that work for them. But they also just wanted more T-shirts. They wanted hats,” Waldhorn said. “Just give them the basics.”

And don’t just “shrink it and pink it,” as has so often been the “answer” for women's merchandise. Or slap a women’s team’s logo on a men’s item. Women’s sports fans want merchandise designed for them and made in styles and fabrics that are comfortable and appealing, and they want the same broad variety of products there are for men’s sports.

This goes beyond clothing items, too. Think key chains and license plate holders. Glasses and mugs. If fans of men’s sports fans want these things, why would decision makers think fans of women’s sports wouldn’t, too?

“The most common assumption is that there isn’t an audience for women’s sports apparel. But that is absolutely not true,” said Megan Gokey, head of B2C marketing in North America and the United Kingdom for Klarna, which is both an online shopping hub and payment processer for e-commerce.

“By putting this out there, we’re really trying to drive awareness that this is actually an issue,” Gokey said. “The opportunity exists, the fans are asking for it, the demand is there. Supply just needs to catch up.”

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While manufacturers and retailers are leaving money on the table, teams and leagues are losing out, too.

When fans wear merchandise, it helps build brand awareness. The New York Yankees and Dallas Cowboys aren’t popular worldwide solely because of their play and history. People wearing their jerseys and T-shirts and caps and jackets played a role, too. Not everybody who sees a Caitlin Clark T-shirt or Alex Morgan jersey is going to buy tickets to a game. But see enough of these items and you might be intrigued enough to check out the team.  

Also, as the women’s sports market grows, teams and leagues might not control their revenue streams from sponsors or broadcasters. But they do control the amount of merch they sell.

“There are so many inequities in men’s sports vs. women’s sports that this is one of the many. But it hasn’t gotten the attention until maybe now,” Gokey said.

The report is designed to get the attention of decision makers, but change will take time. In the meantime, Klarna is creating a women’s sports destination on its website and app so fans will no longer have to hunt for merchandise.

Klarna also partnered with Togethxr, the woman-owned media and merch company, for a limited-edition collection of T-shirts and tote bags. A portion of the proceeds will go to the Women’s Sports Foundation.

"Women’s sports is moving in a very progressive way and rapid direction," said Krieger, who is working with Klarna and Togethxr on the merchandise collection. "If you're not jumping on the bandwagon now, it’s going to be too late."

Sounds like a good slogan for a T-shirt.

Follow USA TODAY Sports columnist Nancy Armour on social media @nrarmour.