2028 Democratic Nomination — Cross-Exchange

The 2028 Democratic nomination is the deepest durable book in prediction markets, and a week after the November 3 midterms it is still trading heavily: $1,631,169 on Kalshi and $637,135 on Polymarket in the last day.

Jon Ossoff has kept his post-election lead. He is 25.5% on Kalshi and 26.85% on Polymarket; Manifold has him at 24.16%. Alexandria Ocasio-Cortez is now alone in second, at 14.5% on Kalshi and 14.25% on Polymarket, with Gavin Newsom third at 11.5% and 10.8%.

The flow has spread out. AOC's Kalshi leg was the busiest in the last day at $110,263, ahead of Ossoff's $90,014 and Newsom's $36,416. Kamala Harris and Pete Buttigieg are tied at 5.25% on Kalshi and 5.35% on Polymarket.

The venues agree within about a point and a half on all three leaders.

Kalshi and Polymarket run the same question, Kalshi at about two and a half times the size in the last day. Read them side by side: Ossoff leads both by eleven to twelve points, AOC sits second on both within a third of a point, and Newsom is third, a few points further back.

Alexandria Ocasio-Cortez priced directly on each side. 14.5% on Kalshi against 14.25% on Polymarket, a spread of a quarter point. She has moved clear of Newsom into second, eleven points behind Ossoff on Kalshi. Her legs took $110,263 and $14,145.

Newsom at 11.5% and Ossoff at 25.5% on Kalshi. In late October they were a point apart; since his Georgia Senate race on November 3, Ossoff's leg has doubled while Newsom's has eased, on $90,014 in the last day against Newsom's $36,416. Ossoff holds $6,106,695 of open interest, the deepest position in the book.

Andy Beshear took $138,380 in a day at 3.8% in late September, and the price followed, to 5.85% in mid-October. It has since settled lower: he is 4.65% on Kalshi, on $23,760.

Polymarket shows the same, Beshear at 3.95% on $3,369. The accumulation that lifted the leg has not resumed.

Adjacent books that extend the story. The Democratic VP nomination turned $36,583 in the last day and is now a flat field: James Talarico at 9.75%, Gretchen Whitmer 9.1%, AOC 8.45%, Mark Kelly 7.3% and Pete Buttigieg 7.2%. Manifold runs an independent nominee book worth reading as a crowd check against the two big exchanges: it has Ossoff first at 24.16%, AOC 14.71% and Newsom 11.33%.

• Ossoff's lead. 25.5% on Kalshi and 26.85% on Polymarket, about eleven points clear a week after the midterms.
• AOC alone in second. 14.5% on Kalshi and 14.25% on Polymarket, with the busiest Kalshi leg in the last day.
• Newsom slipping to third. 11.5% on Kalshi and 10.8% on Polymarket.
• The cross-exchange spread is small. Within about a point and a half on all three leaders.
• Beshear is flat at 4.65% on Kalshi after his September climb and October slide.
• The VP book. No one above 10%: Talarico 9.75%, Whitmer 9.1%, AOC 8.45%.
• Whether the post-election repricing holds as the new Congress forms and the first 2028 moves begin.