Prediction markets top $11B weekly volume as Kalshi takes 90.4% share
Prediction markets reached $11.26 billion in weekly contract volume, a new record, with Kalshi capturing 90.4% market share. Growth was driven by sports and combo markets, according to DeFi Rate. In a separate study, Kalshi said an internal review of 2.2 million data points found prediction markets stayed accurate a week before events with just $50,000 to $60,000 in volume. The study suggests high trading volumes are not necessary for reliable forecasts.
Kalshi's 90.4% share turns a volume record into a liquidity monopoly that reshapes rival strategy. Polymarket, Novig, and Robinhood Derivatives now face a market where one venue clears nine of every ten dollars; matching that depth requires capital commitments most cannot make. Novig's $125 million opening week looked disruptive, but Kalshi's $10-plus billion week reasserts scale dominance. The structure risk is market-maker concentration: if one venue holds virtually all two-sided flow, price discovery may be efficient but competition for spreads collapses.
Rivals must now choose between niche verticals where Kalshi is weak, or costly user-acquisition spends to chip share from a deeper pool. Kalshi's own study undercuts the defensive moat, since it found accuracy at low volume. That finding invites regulators to ask whether a single dominant platform serves price discovery, or merely accumulates rents on a function any smaller venue could replicate.