When we last covered these markets on Oct. 15, 2026, traders were growing skeptical of a blue tsunami in the 2026 midterms. One week before Election Day, much of that skepticism has faded.
The blue tsunami contract is back above an even chance, the blue wave market has edged higher, and a newer mega tsunami market gives Democrats roughly a one-in-four shot at an even bigger night. As of 6:25 p.m. ET on Oct. 28, 2026, traders price a blue wave at 81%, a blue tsunami at 55% and a mega tsunami at 27%.
Blue wave odds at 81%
The blue wave market has been one of the steadier contracts on Kalshi's midterm board. Traders now give Democrats an 81% chance of reaching its thresholds, up 1 point from 80% on Oct. 15, 2026.
That puts it close to where it has spent most of the year. The market sat at 83% in mid-March 2026, jumped from 73.8% to 83.6% over a single week in September 2026 and briefly hit 87% on Sept. 29, 2026, before settling back.
To resolve Yes, Democrats need at least 218 House seats, the number required for a majority, along with at least 49 Senate seats. The latest move suggests traders' confidence in that baseline outcome has held firm heading into the final week.
Blue tsunami back above 50%
The bigger move has come in the blue tsunami market. Traders now put its odds at 55%, a 10-point jump from 45% on Oct. 15, 2026.
It has been the more volatile of the two contracts. The market stood at 53.9% in April 2026, dipped to around 40% in September 2026, surged to 53% by Sept. 29, 2026, and slipped back to 45% by mid-October 2026 before the latest rebound.
A blue tsunami requires at least 235 House seats and at least 51 Senate seats. Democrats would need to win the Senate outright and build a House majority roughly 17 seats larger than the bare minimum. With the contract above 50%, traders now see that outcome as slightly more likely than not.
Mega tsunami odds at 27%
Kalshi's newest rung on the ladder, the mega tsunami market, sets the bar higher still: at least 240 House seats and at least 54 Senate seats.
Traders give it a 27% chance, or roughly one in four. Clearing it would take five more House seats and three more Senate seats than a blue tsunami.
The market opened in late September and has drawn about $172,000 in volume, a fraction of the activity in the blue wave and blue tsunami contracts.
What's the difference between a blue wave, a blue tsunami and a mega tsunami?
All three are combination contracts: each pays out only if Democrats clear both the House and the Senate threshold.
Blue wave: Democrats hold at least 218 House seats and at least 49 Senate seats.
Blue tsunami: Democrats hold at least 235 House seats and at least 51 Senate seats.
Mega tsunami: Democrats hold at least 240 House seats and at least 54 Senate seats.
The thresholds stack, so a mega tsunami would automatically count as a blue tsunami and a blue wave. That is why the odds fall at each step up. All three resolve on the makeup of Congress as of Feb. 1, 2027, and independents who caucus with Democrats, like Sen. Bernie Sanders, count toward the party's total.
Kalshi's seat-count markets offer another reference point. As of Oct. 26, 2026, traders projected Democrats to hold about 238 House seats and 52 Senate seats, which would clear the blue tsunami bar in both chambers but fall short of a mega tsunami.
Where the markets stand one week out
Kalshi traders have grown more confident in a large Democratic win since mid-October. The blue wave market rose modestly, from 80% to 81%, while the blue tsunami made the bigger move, climbing from 45% to 55%.
At 27%, the mega tsunami suggests traders see an even larger sweep as possible but still unlikely.
As of 6:25 p.m. ET on Oct. 28, 2026, Kalshi markets predict:
One week out, the markets are less focused on whether Democrats take Congress and more on how large a majority they could build.
Follow Kalshi on X: @Kalshi | Image source: Mario Tama
The opinions and perspectives presented in this article belong solely to the author. This is not financial advice and does not constitute an offer, solicitation, or recommendation to trade any specific product. Information is provided for convenience only on an "AS IS" basis. Past performance is not necessarily indicative of future results. 18+ only. Restrictions and eligibility requirements apply. Trading event contracts and trading leveraged products, including perpetual futures, involves significant risk and is not appropriate for everyone. Please carefully consider if it is appropriate for you in light of your personal financial circumstances. Kalshi products are not available in all jurisdictions. See kalshi.com/regulatory for more information. Kalshi is subject to U.S. regulatory oversight by the CFTC.
