Kalshi has dramatically reshaped the prediction market landscape by securing distribution deals with major retail brokerages, capturing 96% of non-sports prediction market volume in the week ending September 13. The shift represents a fundamental change in how prediction markets reach everyday traders, moving beyond crypto-native platforms to mainstream financial apps that millions of people already use.

How Did Kalshi Overtake Polymarket So Quickly?

The numbers tell a striking story. Non-sports prediction market volume across Kalshi and Polymarket reached $10 billion in the week ending September 13, marking the sixth consecutive record week. Kalshi drew in $9.6 billion of that total, while Polymarket captured just $344.2 million. This represents a dramatic reversal from just three months earlier, when the two platforms split the market roughly evenly. A year ago, Polymarket actually led the category.

The key difference lies in distribution channels. Kalshi's contracts are now available directly through Robinhood, Webull, Coinbase, and Moomoo, platforms with massive user bases of retail traders who never specifically sought out a prediction market platform. Polymarket, by contrast, still lacks these mainstream distribution partnerships and remains primarily accessible to crypto-native traders who actively seek it out.

What Types of Markets Are Driving the Volume Surge?

The non-sports category on these retail platforms is dominated by short-dated crypto and index markets. Webull's prediction markets page, for example, leads with Kalshi-powered hourly contracts on the S&P 500, Nasdaq, Bitcoin, and Ethereum. These hourly contracts open and settle within 60 minutes, allowing traders to close one position and immediately enter another, generating fresh trading volume every hour the market stays open.

This structure creates a mechanical advantage in reported volume metrics. A dollar sitting in a Robinhood account generating hourly Bitcoin contracts produces far more reported activity than a dollar parked in a long-dated market that settles weeks later, such as a Federal Reserve decision contract. Both types of trades count equally in volume statistics, but the hourly contracts generate multiple data points where long-dated contracts generate one.

• Hourly Crypto Contracts: Bitcoin and Ethereum contracts that open and close within 60 minutes, available on Webull and other retail platforms powered by Kalshi infrastructure.
• Index Futures Contracts: Short-dated predictions on S&P 500 and Nasdaq movements, marketed as accessible alternatives to traditional derivatives for retail traders.
• Multi-Leg Combo Contracts: Bundled predictions combining multiple market legs into a single contract that settles as one unit, with full notional value counted in non-sports volume.

Why Does the Distribution Channel Matter So Much?

Kalshi's dependence on retail broker partnerships creates both strength and vulnerability. The distribution layer is responsible for roughly one-third of Kalshi's daily trading flow, according to the available data. However, this advantage may not be permanent. Robinhood is currently building Rothera, an exchange and clearing venture developed with Susquehanna International Group, designed to let Robinhood list event contracts without relying on a third-party platform like Kalshi in the middle.

If Robinhood successfully launches Rothera as an independent venue, it could redirect a significant portion of Kalshi's volume back to Robinhood's own infrastructure. This would represent a fundamental shift in the prediction market ecosystem, moving power from specialized prediction market platforms to the retail brokerages themselves. The outcome remains uncertain, but the dynamic illustrates how distribution partnerships in prediction markets are not necessarily permanent competitive advantages.

How Are Volume Metrics Calculated Across Platforms?

Comparing prediction market volume across different platforms requires understanding how each one counts trades. Artemis, a data tracker, reads on-chain activity to measure volume. However, Polymarket's CFTC-regulated US venue does not settle on-chain, meaning those trades do not appear in Artemis's $344.2 million figure for Polymarket. Other platforms draw the line between categories differently, splitting crypto contracts, combos, and exotic instruments by their own internal rules.

This measurement inconsistency means the same week can produce noticeably different market share figures depending on which tracker you consult. The directional trend, however, holds consistently across every data source: Kalshi is pulling away from Polymarket in non-sports volume. The precise size of the lead varies by methodology, but the direction of travel is unmistakable.

The prediction market industry is entering a new phase where retail accessibility and distribution partnerships may matter more than platform features or user experience. Kalshi's current dominance reflects not necessarily superior technology, but superior access to the everyday traders who use Robinhood, Coinbase, and Webull. Whether that advantage persists depends on whether those brokerages decide to build their own prediction market infrastructure or continue outsourcing to specialized platforms.