World Series contracts top $140M combined on Kalshi and Polymarket

Kalshi accounts for most of the volume

World Series contracts on Kalshi and Polymarket have generated more than $140M in combined trading volume, according to Covers, with Kalshi accounting for the larger total.

Covers tracked Kalshi’s cumulative volume rising from $84.7M to $100M, while Polymarket’s increased from $41.4M to $42M. Those figures place Kalshi ahead both in overall activity and in the increase between the reported readings.

More than $15M traded during the 24 hours ending Tuesday noon, according to Covers. That short-window figure provides a separate measure of activity from the platforms’ cumulative totals.

Dodgers lead the field

Covers identifies the Dodgers as the leading team on both platforms and the Brewers as their strongest challenger ahead of the MLB postseason. The supplied material does not include contract prices or implied probabilities, limiting any comparison of how strongly the two markets favor either team.

The timing also warrants care: the supplied publication timestamp is Oct 13, 2026 · 11:09 PM ET, but the underlying Covers source is dated September 29, 2026. The reported volumes and team rankings should therefore be treated as a source snapshot, rather than verified October 13 readings.

What it means for prediction markets

• Activity is concentrated on Kalshi: Its reported $100M total substantially exceeds Polymarket’s $42M.
• Volume is not a probability signal: The trading totals alone do not establish whether confidence in the Dodgers or Brewers increased.
• Freshness matters: The source-date discrepancy and absence of contract prices limit conclusions about current market positioning.