Kalshi Sets Weekly High $4.1B Volume as Polymarket Continues Slide to $1.6B

Kalshi posted its highest single-week notional quantity on report through the week ending May 4, tallying $4.13 billion, up 8.5% from $3.81 billion the prior week. Polymarket fell 6.2% WoW to $1.60 billion, its lightest week since late March. Kalshi now holds 72.1% of mixed notional quantity between the 2 platforms, up from 69.0% the week prior and from near parity in late February and early March.

As not too long ago as the week of March 23, Polymarket was processing considerably extra transactions than Kalshi (26.3M vs. 19.0M), however that has totally reversed.

Kalshi vs. Polymarket head to head: Week of May 4

Kalshi’s notional quantity lead over Polymarket has widened steadily because the begin of April. Kalshi held a roughly 3-to-2 benefit with $2.90B vs. $1.97B the week of March 30. That has since stretched to greater than 2.5-to-1 at $4.13B vs. $1.60B. The divergence accelerated sharply in April. While Kalshi added roughly $1.2B in weekly quantity over the six-week window, Polymarket shed about $370M. The transactions shift is much more stark. From the week of March 23 to May 4, Polymarket and Kalshi flip-flopped positions, with Kalshi at 24.3M to Polymarket’s 15.8M for a swing of roughly 17 million transactions in six weeks.

This is a continuation of a pattern we first flagged within the March volume report and that accelerated via Kalshi’s April record $14.81B monthly total. What’s modified in current weeks is Polymarket’s decline spanning all main classes. It’s not simply crypto and politics quantity softening, however sports activities quantity pulling again too, down from $786M the week of April 27 to $725M the week of May 4, even with the NBA playoffs in full swing. Kalshi’s sports-first mannequin, bolstered by the rising Exotics (combos/parlays) product, helps drive Kalshi’s lead in each general quantity and transactions.

Top platforms snapshot

A weekly snapshot of the 2 high prediction markets platforms plus Polymarket US clearly reveals the US-facing change’s infancy. Polymarket US remains to be not close to the size of the opposite two, however weekly charges have gotten a major income driver.

Kalshi taker quantity of $1.41B was up 5.7% week-over-week from $1.33B, in accordance to Dune data, in line with the notional quantity acquire. Transaction depend grew 4.9% to 24.3M, persevering with a gradual climb that has added roughly 4 million weekly transactions since March 30.

Despite its continued four-week quantity slide, Polymarket world taker quantity of $732M was up 6.6% from $686M the prior week. That uptick is partly a perform of market settlement with a high quantity of huge markets closing in the identical week (UFC 328, Barcelona-Real Madrid, Bayern-PSG, a number of NBA first-round video games). Transactions additionally rose 6.8% to 15.8M from 14.8M. Fees of $3.15M have been down 48.5% from $6.12M the prior week, a a lot steeper drop than the 6.6% taker quantity acquire would indicate. The possible rationalization is that the markets resolving this week have been lower-stakes, lower-fee occasions in contrast to what settled the week prior, quite than a slowdown in new buying and selling exercise. Polymarket not too long ago rolled out a platform-wide fee expansion on March 30.

Polymarket US was the week’s clear delicate spot and value watching individually. Taker quantity collapsed 78.9% week-over-week from $125.6M to $26.5M, transactions fell 73% from 1.2M to 326K, and charges dropped 77.9% from $2.34M to $517K. The significant drop throughout each metric concurrently is shocking contemplating the NBA and NHL playoffs are in full swing. It could possibly be partly a results of fewer NBA video games in Round 2 of the playoffs in contrast to Round 1. Whether it additionally displays a structural pullback or one thing else isn’t totally clear from the info alone, however the magnitude of the transfer in a single week is notable and value monitoring within the coming weeks.

On charges broadly: mixed Polymarket + Poly (US) charges of $3.67M have been down from $8.46M the prior week. Including Limitless, predict.enjoyable, and Opinion, whole non-Kalshi platform charges got here to $3.97M, down 59% from $9.69M and the bottom weekly charge whole within the dataset. Limitless dropped 79.6% to $228K regardless of growing notional volume, which suggests doable charge price compression, inflated buying and selling volumes, or one thing else happening structurally.

Kalshi vs. Polymarket class breakdown May 4-10

Kalshi continues to dominate on sports activities, however issues get extra attention-grabbing throughout different high classes. Notably, Kalshi has surpassed Polymarket on crypto market quantity, maybe shocking contemplating Polymarket’s blockchain-based construction. Also noteworthy is Polymarket’s large lead on the Politics (together with Trump) class (92.6% share) and vital 3-1 share lead within the smaller classes of Entertainment/Culture and Economics.

Notes: Notional quantity from Dune Analytics. Exotics rolled into Sports for Kalshi totals; Trump markets rolled into Politics for Polymarket totals. Cross-platform share calculated for Kalshi + Polymarket mixed.

Polymarket vs. Kalshi market share on high classes

Sports: Kalshi’s core sports activities notional grew 5.7% week-over-week and, mixed with Exotics, held 82.4% of cross-platform sports activities quantity. The NBA playoffs have been the dominant driver. OKC Thunder markets appeared throughout 4 of Kalshi’s high 20 by weekly quantity, in accordance to our prediction markets volume tracker, led by the Pro Basketball Champion market, which carried the best open curiosity on the Kalshi board by a large margin.

Polymarket’s sports activities quantity fell 7.8% week-over-week regardless of the playoffs, and its high sports activities market was the 2026 FIFA World Cup, which dwarfed something on the Kalshi sports activities slate. The distinction displays how in another way the 2 platforms’ consumer bases have interaction with sports activities, Kalshi main on the sport and collection degree and Polymarket quantity concentrating on the worldwide event degree.

Exotics: The combo/parlay product was the standout development story at Kalshi, up 23.2% week-over-week to $511.6M in notional quantity, lifting its share of the mixed sports activities + Exotics bucket to 15.0% from 13.1% the prior week. We’ve been monitoring this as a structural driver for a number of weeks now, and the trajectory is holding. Expect it to develop considerably as soon as NFL begins again up within the fall.

Crypto: The best class between the platforms at 55/45 in Kalshi’s favor is Crypto. Kalshi’s crypto notional quantity rose 14.4% week-over-week whereas Polymarket’s edged up simply 2.1%. Kalshi’s crypto markets are primarily pushed by Bitcoin markets, each day by day and longer-term worth goal markets, however they’re gaining in recognition.

Politics: Polymarket continues to dominate Kalshi on Politics by a large margin, holding 92.6% of mixed cross-platform political notional quantity. Both platforms noticed politics quantity soften week-over-week with Kalshi down 9.9% and Polymarket Politics + Trump down 8.1%, however the absolute ranges stay vastly completely different. Polymarket’s slate was anchored by the US-Iran peace deal, each 2028 presidential nomination markets, and the 2028 presidential election.

Kalshi’s politics exercise has a extra home make-up, pushed final week by LA Mayor, California Governor, and House control in 2026 midterms, with no particular person market approaching Polymarket’s high politics volumes. Interesting to notice that Kalshi’s 2028 Democratic Nominee market carries substantial open curiosity on comparatively gentle weekly stream, pointing to long-duration positioning quite than energetic buying and selling.

What we’re watching

The post-Masters dip we flagged for the week of April 13 seemed like a possible inflection level, however Kalshi bounced to a brand new report whereas Polymarket has continued decrease. Going into May, the query is how the NBA Finals and the 2026 FIFA World Cup, which kicks off in June, shift the steadiness. World Cup markets are already exhibiting $327.2 million in 30-day buying and selling quantity, with 99.3% coming from Polymarket in accordance to our tracker.

Kalshi’s sport and collection markets, mixed with parlay depth, positions it effectively to maintain present ranges via the NBA Finals and Stanley Cup Finals. How every platform captures World Cup quantity might be a defining check within the sports activities class this summer time. Meanwhile, the PGA championship is that this week, and the French Open kicks off subsequent week, two main quantity drivers particularly for Kalshi.

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