A study of 547 million NFL wagers found that parlays went from about a third of bets to nearly 73% in five years. New bettors weren’t the only reason. Existing customers changed how they bet, too.
In Las Vegas, parlays used to come in Day-Glo. It was a marketing tactic casinos used back in the mid-2000s to get customers to notice them.
After all, place a stack of bright fluorescent parlay cards in hotel lobbies and guest rooms, and they’re going to be hard to miss.
Two decades later, sports betting is legal across much of the United States, and sportsbooks don’t have to wait for bettors to walk past a stack of parlay cards. Instead, operators can push same-game parlays, ready-made combinations, and other multi-leg bets right to their phones.
Yet as recently as 2018, single-leg bets still made up about two-thirds of the NFL wagers in one major U.S. sportsbook’s data.
However, by 2023, those numbers had almost completely flipped, with parlays making up 72.51% of wagers, while single-leg bets had dropped to 27.49%.
And this change didn’t come about just because sportsbooks had attracted new customers who preferred parlays. The sportsbook’s existing customers were changing how they bet, too.
That’s according to a study published in Finance Research Letters in September 2026. After analyzing 547 million NFL wagers placed between 2018 and 2023, researchers found that bettors were placing a larger percentage of their bets as parlays. By 2023, that percentage was nearly 39 percentage points higher than in 2018.
The findings make it clear that a shift happened, but what they can’t tell us is why.
A newly published companion study in the Journal of Gambling Studies offers one piece of the puzzle. In that study, researchers found that bettors placed a greater share of their wagers as parlays during periods when sportsbooks were running promotions.
However, the researchers noted that the findings don’t necessarily prove promotions were responsible for the shift.
So the question remains: What turns someone who once mostly placed single-leg bets into a parlay bettor?
Existing Bettors Placed More of Their Bets as Parlays
The betting preferences of a sportsbook’s customers aren’t static. An influx of new customers can be enough to change a sportsbook’s overall betting mix.
To determine whether new customers were the reason for the increase in parlays, the authors of Contract Choice, Parlay Adoption, and Sportsbook Margins looked into whether existing bettors were changing how they wagered, too.
“What stood out was how much existing bettors changed their behavior,” Richard Borghesi, a professor of finance at the University of South Florida and lead author of the study, told Gambling Insider.
“New customers were part of the story, but they could not fully explain the growth.”
Traditional parlays increased from 33.59% of wagers in 2018 to 40.46% in 2023. Over that same period, same-game parlays went from 0% to 32.05%.
“Same-game parlays accounted for most of the overall increase, but the pattern suggests a broader movement toward combining bets and pursuing larger potential payouts,” Borghesi explained. “It does not establish whether SGPs helped encourage that broader movement.”
However, there’s still a lingering question the data can’t answer: why bettors changed their behavior.
“We can observe what people bet, but not what they were thinking,” Borghesi said.
Parlay Use Rose During Sportsbook Promotional Periods
Borghesi and his colleagues didn’t stop with the first study. They followed it with a second one that looked at whether sportsbook promotions could help explain the increase in parlays.
Sportsbook Promotions and the Growth of Parlay Wagering uses the same sportsbook data but adds information on when bettors used bonuses, free bets, and profit boosts.
Bonuses made their first appearance in the data in 2021, followed by free bets in 2022 and profit boosts in 2023.
By the time 2023 rolled around, the percentage of wagers bettors placed as parlays was about 19 percentage points higher than during the 2018–2020 period.
What’s interesting is that the increase wasn’t limited to wagers that actually took advantage of those promotions. When researchers removed bets placed with bonuses, free bets, or profit boosts, parlay use remained roughly 17 percentage points above its pre-2021 level.
“Our companion study gives promotions some empirical support: their introduction coincided with increased parlay use, even after removing promotional wagers,” Borghesi told us.
“But we cannot confidently rank these explanations or conclude that promotions caused the shift.”
Sportsbook Apps Made Parlays Easier to Build and Easier to Find
Promotions weren’t the only thing changing at sportsbooks during the years covered by the study. The way bettors built and found parlays was changing as well.
Matt Bresler, co-founder and CEO of sports betting content company Odditt, told Gambling Insider that in 2018, a typical parlay meant combining spreads, totals, or moneylines from several different games.
“Same-game parlays have completely changed that,” Bresler said. “Once books could price bets inside one game that depend on each other, like a quarterback’s passing yards and his team winning, you could build a parlay around the one game you actually cared about.”
As the products changed, the apps changed along with them. Player props added even more markets bettors could combine, while sportsbook apps made it easier to put those selections together.
“You tap three or four picks, and they land on the bet slip together,” Bresler said. “Some books have put ready-made parlays on the home screen or the game page, so you don’t have to build anything. So yeah, it’s a lot easier for a singles bettor to try one.”
Bettors May Move Toward Parlays as They Get More Familiar With Sports Betting
While parlays have become easier to build, there’s also the question of what makes someone who usually places single bets want to try one.
Speaking to Gambling Insider, Anthony Lucas, a professor at UNLV’s William F. Harrah College of Hospitality who spent 10 years working in the casino industry before moving into academia, described the progression he’s seen among sports bettors.
“Most people will start making what we call straight bets, which are picking a side, like which team will win,” Lucas said.
But when it comes to parlays, something different is on offer.
“What the parlay does is it allows you to bet less money, risk less money, and then if you hit it, you get a bigger payout,” he said. “So I call it the something-for-nothing proposition.”
Lucas compared the appeal of parlays to other types of gambling, including slot jackpots and long-shot bets at the racetrack, where a relatively small wager can potentially lead to a much bigger payout.
“They [exotic long-shot bets] have the same something-for-nothing proposition, which is, ‘I can make a little bet, and if I win, I’m going to get a big payout,’” Lucas said. “And that’s really what drives parlays.”
Becoming more familiar with sports betting may also help explain why a bettor who starts with single bets eventually branches out.
Lucas pointed out that the study’s starting point, 2018, was also the year the Supreme Court overturned the Professional and Amateur Sports Protection Act (PASPA) and regulated sports betting began spreading across the U.S.
“People were kind of learning about sports wagering, and so they would make traditional bets, like side bets, picking a team,” Lucas explained. “Then they start to get more involved, and they’re like, ‘Oh, this parlay is attractive.’”
Sportsbooks Can Learn Who Likes Parlays and Put More of Them in Front of Those Bettors
Once someone starts placing parlays, sportsbooks get a window into their betting preferences thanks to the data those wagers generate.
Adam Bjorn, CEO of Plannatech, which operates Prime Sportsbook and Betcris, told Gambling Insider that a customer’s betting history can show operators whether they place parlays and how they build them.
“Bet history tells you almost everything: stake sizes, sports, markets, how many legs someone builds, and whether they’re chasing a big payout or grinding a small edge,” Bjorn said. “Once you know someone is a parlay player, you put parlays in front of them.”
After they place that first parlay, a bettor might start seeing more of them in the app as the sportsbook learns about their preferences.
Operators also have quite a few ways to encourage bettors to try out a parlay in the first place.
When we asked Bjorn whether sportsbooks actively try to move bettors from single bets to parlays, he didn’t hesitate:
“Of course they do, with odds boosts, parlay insurance, bonus bets tied to multi-leg tickets, and above all, placement,” Bjorn said. “Make the parlay the easiest thing to click on the screen.”
There’s also a financial incentive to do so. Bjorn said sportsbooks generally hold somewhere in the mid-single digits on straight bets, compared with 20% to 30% on same-game parlays.
“The math explains the push,” he said. “Parlays are the most profitable product in the building, so the industry will keep putting them front and center.”
Bjorn also sees promotions as a way to get bettors to try a format they may already find appealing.
“The promo doesn’t create the appetite; it unlocks it,” he said. “Well over 95% of bettors are recreational, and they all want the same thing: put down a toothpick to win a lumberyard. It’s the lottery mentality: $5, $10, $20 for a shot at hundreds, thousands, sometimes tens of thousands.”
And that initial nudge from a promotion can be just enough for a bettor to keep going.
“A boost or a bonus token gets someone to try it on the app, and after the first ticket, they don’t need the promo anymore,” Bjorn told us.
What Makes Bettors Move From Single-Leg Wagers to Parlays?
There’s no single moment when a switch flips and someone suddenly becomes a parlay bettor.
Instead, the change seems to happen more gradually. A bettor who starts out picking a team to win gets comfortable with the idea of betting as they place more wagers. Parlays become easier to find and build, with the added appeal of a big payout for a small wager.
There’s also the promotion and boost factor, which can give a person a reason to try a parlay for the first time. And once they do, the sportsbook has more information about what they like and can keep putting those bets in front of them.
We can’t attribute these changes to any one of those things. The research shows that bettors changed how they wagered. What it doesn’t do is tell us exactly how much of the shift resulted from changing bettor preferences, sportsbook marketing, or the ways the two may have reinforced each other.
What it does suggest is that someone moving from single-leg bets to parlays may be less about one big decision and more about a series of small ones.
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