Polymarket Trader Could Collect $3M if Republicans Defy Midterm Odds

Key Takeaways

A $183,000 Bet on a Republican Sweep

A Polymarket account trading as colombiaman bought 2,895,931 shares on a Republican sweep of Congress on Monday, betting that Republicans will hold both the Senate and the House in Tuesday’s midterm elections. The shares cost about $176,200 at an average of 6.08 cents, plus about $6,600 in fees, in Polymarket’s balance-of-power market for the 2026 midterms. Each share pays $1 if Republicans keep both chambers, so the position would return about $2.9 million.

The account also bought 145,336 “No” shares on a Democratic sweep for about $42,200 including fees, at an average of 28 cents. Those pay out if Democrats fail to win both chambers. If Republicans keep Congress, the two bets together would return about $3.04 million on roughly $225,000 spent across the account’s trades, a profit of about $2.8 million. If control of Congress is split, only the second bet pays, leaving the account down about $80,000, excluding a small Texas bet.

The account, created in August, made its first trade at 18:12 UTC on Monday and finished buying the sweep shares four minutes later. It is now the largest holder of that outcome, ahead of accounts holding 2.1 million and 1.8 million shares. Its only other trade outside the two sweep bets was a roughly $660 bet, at 25 cents, against Democrats winning Texas’ Senate race. By Tuesday morning, Polymarket’s displayed price for the sweep had slipped to 5.5 cents, and Polymarket valued the main position at about $159,300.

On Tuesday morning, Polymarket priced a Republican sweep at 5.5%, against 76.5% for a Democratic sweep and 19.5% for a Republican Senate with a Democratic House. Kalshi had a Republican sweep at about 6.4%. Forecasters agreed. Nate Silver’s FLIPR model said in its final update on Tuesday that a Democratic House majority “looks all but certain” and that “the polls indicate that they should also win the upper chamber.” Silver Bulletin’s forecast gave Democrats an 80.1% chance of taking the Senate, Newsweek reported Monday. The RealClearPolitics average, covering polls through Oct. 26, had Democrats ahead by 8.2 points on the generic congressional ballot. Going into Election Day, both Kalshi and Polymarket favored Democrats to win both chambers, and pollsters pointed the same way. Polymarket’s balance of power event has drawn about $60.9 million in trading volume.

There is no public indication that the account’s trades are under review, but election betting more broadly is drawing scrutiny: Polymarket has investigated dozens of bets tied to the midterms, and Kalshi and Polymarket face a Tuesday deadline to answer questions on election insider trading from Sens. Elizabeth Warren, D-Mass., and John Curtis, R-Utah.