The year started with a whisper and ended with a roar for prediction markets as combined notional volume surpassed $4.9 billion for the week of Dec. 29, led by Opinion Labs, Kalshi and Polymarket, respectively.

As 2026 begins, the data suggests prediction markets are comfortably out of their exploratory phase and into a full-on growth sprint, posting record notional trading volumes in each of the final six weeks of the year (since Thanksgiving week). Meanwhile, onchain prediction exchange Opinion has become too big to ignore from a volume standpoint. Opinion posted $1.81 billion in notional volume to close out the year, putting it second only to Kalshi, though Kalshi and Polymarket remain the most institutionally relevant platforms for mainstream adoption.

Both Kalshi and Polymarket also posted weekly all-time highs this past week, Kalshi with $1.98B and Polymarket with $1.45B.

The data, originating from Dune Data Dashboards and tracked by DeFiRate.com, includes top onchain platforms as well as the leading non-blockchain exchange, Kalshi. Note that not all prediction platforms are currently tracked by Dune.

Based on tracked platforms, Kalshi led the week in raw notional volume, and together with Polymarket accounted for 74.5% of total weekly volume. A further data dive reveals some key nuances across platforms, highlighted below.

Dune’s historical data shows tracked prediction exchanges hovering around $500M in total weekly notional volume through the first three quarters of 2025. Unsurprisingly, the steep climb to over $5B in weekly volume (an increase of more than 10x) began in the first week of NFL (the week beginning Sept. 1). Meanwhile, the recent volume peak coincided with the final week of NFL regular season and the college football playoff (CFP) quarterfinal games.

In the final six weeks of 2025, weekly total market volume consistently ranged between $3.7B–$4.9B, with each subsequent week outpacing the previous one. Some additional takeaways:

Kalshi and Polymarket fluctuated in terms of which platform led from week to week, with Opinion Labs establishing itself as a top-three platform in terms of total notional volume quickly after launching and remaining among the top three in every week since. Still, a look at weekly users and number of transactions shows Kalshi and Polymarket still well ahead.

While Opinion Labs outpaced Polymarket’s weekly notional volume by 25% during the week of Dec. 29, Polymarket had 217% more weekly users (214,962 vs. 67,913). Note: Kalshi is excluded from this chart.

Meanwhile, weekly transactions also show Kalshi and Polymarket as the two runaway market co-leaders:

Open interest comparisons paint a similar picture, with Kalshi and Polymarket typically more than 2.5x higher than open interest on Opinion’s onchain exchange.

Launched in closed beta in September before officially debuting on the BNB blockchain in October, Opinion Labs quickly rose to a top-three volume-driver, first overtaking Kalshi and Polymarket in weekly notional volume the week of Nov. 10, 2025. 

Proud of our portfolio project @opinionlabsxyz hitting a major milestone: $10B in total trading volume + $100M open interest in just 54 days.
The fastest-growing prediction market on record.

Opinion (orange) has even briefly overtaken Polymarket (blue) in national volume share… https://t.co/CHfpD5myPX pic.twitter.com/5lQpcTk9RI

Opinion’s exchange is structurally distinct in user intent and market design, and based on the market data, consists of a smaller number of users with much higher average transactions compared to Kalshi and Polymarket. While Kalshi and Polymarket remain the most institutionally relevant platforms, Opinion’s rapid growth shows there is room for new entrants to drive meaningful volume without necessarily cutting significantly into the growth of established platforms.

The Kalshi vs. Polymarket dynamic remained extremely tight and competitive in the final stretch of 2025. Despite the rise of Opinion Labs and dozens of smaller onchain and centralized, CFTC-regulated platforms across the prediction markets space, Kalshi and Polymarket continue to command the most mainstream attention, transactions and market liquidity.

While Polymarket is still working on fully rolling out its US-facing prediction market exchange, its global onchain platform continues to grow to new heights (alongside Kalshi), thanks in large part to the growth of sports markets.

From the week of Dec. 29, Kalshi tallied $533.6 million more (+36.9%) in notional volume than Polymarket. Here’s a comparison of the two platforms for the week:

It’s no secret that Kalshi’s extreme volume growth has been driven in large part by sports, particularly football markets, which helps explain Kalshi pulling away in volume during the biggest sports betting weeks. Kalshi’s open interest and weekly transactions are also spread across many more active markets (153K compared to Polymarket’s 20K). With so much of its total volume and open interest concentrated in sports markets, many of Kalshi’s open markets in other categories are much more thin in liquidity.

Sports, crypto and politics continue to dominate in volume across platforms, with sports a much more core driver for Kalshi (compared to Polymarket). Compare the notional volume across top categories for Kalshi vs. Polymarket below:

Sports markets are characterized by high liquidity and frequent settlement cycles, helping to drive up Kalshi’s volume and transaction numbers during peak sports seasons and events. Based on the sports calendar, upcoming dips would be expected the week before the Super Bowl when there are no NFL games, and the period between the Super Bowl and March Madness (college basketball) tipoff.

While sports also dominate at Polymarket, the platform has a much more even distribution across sports, crypto, politics, culture and macro financial/economic markets. See the full category breakdowns for Kalshi and Polymarket below.

As more competitors continue pouring into the prediction market landscape, expect the total overall volume and number of users to continue to balloon, along with mainstream adoption. It remains to be seen whether any platform will be able to rival the established behemoths Kalshi and Polymarket, which continue to grow with each new retail partnership.

The post Prediction Markets Record All-Time High $5.3B Volume to End 2025 appeared first on DeFi Rate.

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