As of October 24, 2026, 06:36 PM ET, Polymarket traders price Jim Costa (D) at 94.8% in CA-21 House Election Winner — $39.9K traded so far.
The leading outcome, Jim Costa (D), is priced at 94.8%.
Price changes for the leading market — 24 hours: -0.1 pts; past week: -1.2 pts; past month: +1.4 pts.
Since January 28, 2026, Jim Costa (D) has traded between 48.5% and 97.4%. It opened at 48.5% and last traded at 94.8%.
| Day | Close |
|---|---|
| Oct 15, 2026 | 96.2% |
| Oct 16, 2026 | 95.6% |
| Oct 18, 2026 | 95.8% |
| Oct 19, 2026 | 96.0% |
| Oct 20, 2026 | 96.1% |
| Oct 23, 2026 | 94.8% |
| Oct 24, 2026 | 94.8% |
Jim Costa (D) is favored at 94.8%.
| Outcome | Price | Implied probability | 24h change | Volume | Volume share |
|---|---|---|---|---|---|
| Jim Costa (D) | 95¢ | 94.8% | -0.1 pts | $17.7K | 44.3% |
| Kyle Kirkland (R) | 5¢ | 5.0% | +0.5 pts | $22.2K | 55.7% |
See the full live book for this market on Polymarket
The leading market's spread is 2¢ (bid 94¢ / ask 96¢) — a tighter spread means cheaper round-trip trading.
$39.9K has been traded on this event in total, $594 of it in the last 24 hours, across 8 markets.
This market is scheduled to end November 03, 2026, 11:59 PM ET.
This market will resolve according to the party of the candidate who wins the CA-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026. A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat or Republican parties will be considered a member of one of these parties based on the party with which they most recently expressed their intent to caucus at the time all of the House elections are conclusively called by this market's resolution sources. This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).
Resolution source: https://www.fec.gov/
The largest current holder of the leading market holds 800 shares of Yes.
| Holder | Outcome held | Shares | Value at current price |
|---|---|---|---|
| Raw-Affect | Yes | 800 | $759 |
| 0xa5ef39c3… | No | 635 | $33 |
| Angelic-Enemy-Weeder | Yes | 632 | $599 |
| Lighthearted-Relation | No | 394 | $20 |
| Prickly-Eyrie | No | 390 | $20 |
| Belated-Glue | No | 341 | $18 |
| Handy-Ruffle | Yes | 300 | $285 |
| Little-Gold | Yes | 196 | $186 |
| Evil-Row | No | 119 | $6 |
| Those-Skywalk | Yes | 100 | $95 |
| Time | Outcome | Side | Price | Size |
|---|---|---|---|---|
| Oct 24, 10:06 AM ET | No | BUY | 5.2% | $1 |
| Oct 24, 10:06 AM ET | No | BUY | 5.2% | $2 |
| Oct 24, 03:42 AM ET | No | BUY | 5.2% | $0 |
| Oct 24, 02:47 AM ET | No | BUY | 5.2% | $2 |
| Oct 24, 02:47 AM ET | No | BUY | 5.2% | $1 |
| Oct 23, 11:55 PM ET | No | BUY | 5.2% | $0 |
| Oct 23, 11:55 PM ET | No | BUY | 5.2% | $0 |
| Oct 23, 09:32 PM ET | No | BUY | 5.6% | $4 |
| Oct 23, 09:32 PM ET | No | BUY | 5.6% | $2 |
| Oct 23, 06:57 PM ET | Yes | BUY | 5.2% | $3 |
As of October 24, 2026, 06:19 PM ET, the leading outcome is Jim Costa (D) at 94.8%. Next is Kyle Kirkland (R) at 5.0%. See the live book on Polymarket: https://polymarket.com/event/ca-21-house-election-winner?via=bro
$39.9K in total volume, with $594 traded in the last 24 hours across 8 markets.
The market is scheduled to end November 03, 2026, 11:59 PM ET. It resolves based on https://www.fec.gov/.
Jim Costa (D), priced at 94.8% as of October 24, 2026, 06:19 PM ET. Prices are implied probabilities backed by real-money trading.
Browse the live odds index, today's biggest movers, and Whale Watch for the largest positions.
Prices move fast. Check the live book, read the resolution rules, and size small while you learn.
Sign Up on PolymarketNew here? Start with the complete beginner guide, then run any stake through the payout calculator before you trade.