Kalshi Sheds 50% Volume on Light Sports Calendar as Polymarket US Bounces Back

Kalshi notional quantity fell 49.5% week-over-week to $2.09B for the week starting May 11, its sharpest single-week decline within the dataset, after hitting a report $4.13B the prior week. Polymarket international held comparatively regular, dipping simply 1.7% to $1.58B, its most resilient week relative to Kalshi in over a month. Kalshi’s share of mixed Okay+P notional fell from 72.1% to 56.9% in a single week.

The calendar explains most of it, with no UFC occasion, an NBA between-series lull, and a lighter home sports activities slate all hit Kalshi disproportionately given its sports-heavy combine. Polymarket’s flooring held up as a result of the FIFA World Cup continued to construct and end-of-season European soccer supplied sustained quantity. Polymarket US reversed its prior-week collapse with taker quantity up 123.4% and transactions greater than doubling week-over-week.

Kalshi vs. Polymarket head-to-head

Kalshi’s drop snapped a five-week streak of positive aspects and introduced quantity again to late-February ranges. Polymarket international outpaced Kalshi on transactions (15,858,566 vs. 13,045,511) for the primary time since early April, a reversal from the 24.3M vs. 15.8M hole only one week prior. The six-week pattern nonetheless reveals Kalshi rising its share structurally, however the week of May 11 is a transparent reminder of how calendar-dependent that quantity is.

Top platforms snapshot: Week of May 11

Kalshi notional fell 49.5% and taker quantity dropped 50.2% to $701M, each transferring in lockstep, pointing to a volume-driven decline somewhat than a combination shift. Transactions fell 46.4% to 13,045,511.

Polymarket international held pretty regular throughout metrics for the week. Notional quantity was down simply 1.7%, taker quantity was down 11.1% to $651M, and transactions primarily flat at +0.3%. Fees of $6.83M have been up 4.9%, the one main platform to submit a charge improve. The taker quantity hole between the 2 platforms narrowed from $677M the prior week to only $50M. Note: Polymarket’s class breakdown whole ($1.37B) is decrease than reported notional ($1.58B), possible reflecting quantity in unmapped classes not captured within the Dune data breakdown.

Polymarket (US) reversed sharply after final week’s collapse. Its notional quantity climbed 91.6% to $140.2M, with taker quantity up 123.4% to $59.3M, and transactions up 106% to 672,054. More on this under.

On charges: Kalshi’s $17.85M on $2.09B of notional implies a considerably greater charge price than Polymarket’s $6.83M on $1.58B. For a full breakdown of prediction market charge constructions, see our fees tracker.

Kalshi and Polymarket class breakdown: Week of May 11

Core sports activities on Kalshi fell 50.3% whereas Exotics dropped even tougher at 63.8%, compressing Exotics’ share of the mixed sports activities bucket from 15.0% to 11.4%. The NBA finals second spherical had gaps between collection video games and there was no key UFC occasion to anchor quantity as UFC 328 did the earlier week.

According to our inside prediction market volume tracking, Kalshi’s Pro Basketball Champion market remained No. 1 however fell from $8.4M to $6.0M in weekly quantity, with open curiosity dropping from $76.5M to $45.9M. Colorado Avalanche changed Carolina Hurricanes as the Stanley Cup favourite, and an NBA Finals Matchup market (OKC vs. NY) entered the highest 20.

The IPL Champion market at No. 13 is price a observe as nicely. International cricket breaking into Kalshi’s high 20 indicators a broadening scope past home sports activities. Polymarket sports activities fell simply 7.9%, with the FIFA World Cup surging 74% to $84.3M and heavy end-of-season European soccer quantity offering a flooring. The PGA Championship was one other notable market this week, driving $333.5 million in notional quantity at Kalshi. Polymarket’s comparable market confirmed practically $9.0 million in quantity, highlighting as soon as once more the sports activities hole on main US-based sporting occasions.

Kalshi class breakdown

Polymarket class breakdown

Kalshi politics fell 45.2% to $20.4M however climbed the rankings comparatively. The platform had some political markets crack the highest 20 for the previous week, together with LA mayor race at No. 2, KY-04 Republican major at No. 3, and a “What will Trump say this week?” market at No. 17. On Polymarket, Politics fell 29.0% whereas the Trump class dropped a steeper 44.8%, partly as a result of US-Iran peace deal resolving after producing $26.7M the prior week.

Crypto was down on each platforms: Kalshi -35.7% to $249.6M, Polymarket -10.9% to $279.8M. After Kalshi not too long ago took over the lead in crypto quantity, Polymarket is again up high, albeit marginally. Four separate every day Bitcoin value markets on Polymarket drove notable quantity throughout the week.

Another key transfer through the week of May 11 got here from the tradition and leisure class. Culture on Polymarket surged 151.3% to $66.6M, pushed by Eurovision Winner 2026 closing (Finland led at 47%) and the Elon Musk tweet depend market ($6.6M). On Kalshi, Entertainment was the one class to develop, up 44.3% to $13.3M, pushed primarily by the Survivor Season 50 market.

Note: DeFi Rate’s high class knowledge relies on USD-at-price quantity, or precise {dollars} traded, somewhat than notional quantity, which values every contract at $1 no matter buying and selling value.

Polymarket US rebound

After collapsing 79% on taker quantity the prior week, Polymarket US rebounded exhausting. The high 20 was all sports activities, with 18 of 20 markets already closed. NBA second spherical dominated (Detroit vs. Cleveland, OKC vs. Lakers), adopted by MLB sport markets, Italian Open tennis (Sinner vs. Medvedev), the PGA Championship, and esports breaking in for the primary time with Counter-Strike IEM Atlanta and LoL LPL each within the high 20.

The breadth of the slate drove the rebound. Going into the NBA Finals in June, the query is whether or not the US product can maintain this exercise stage or whether or not it stays extremely event-dependent.

What to observe

The week of May 11 was a type of take a look at for Kalshi quantity and not using a main sports activities driver, and quantity dropped practically in half, regardless of NBA playoffs persevering with and the PGA championship enjoying out. The NBA Finals and FIFA World Cup in June are the subsequent main catalysts, with the NBA semi-finals tipping off this week.

Through two full weeks, Kalshi is averaging $3.11B/week in May towards April’s $3.70B/week tempo that produced a record $14.81B monthly total. Matching that can require a significant back-half rebound. The NBA Finals, upcoming French Open, World Cup lead-up and key 2026 primaries might assist push the platform, however it possible gained’t be sufficient to surpass final month’s report. Polymarket is additional off tempo at $1.59B/week towards April’s $2.25B/week, and at present trajectory is unlikely to match final month’s $9.01B and not using a important catalyst. How each platforms reply to the June sports activities calendar together with NBA Finals, FIFA World Cup and Stanley Cup will set the tone for what has been a steadily widening volume gap since March.

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