Cardinals vs Reds Prediction Market Odds, August 20, 2026
| Spread | Total | ML | Best ML | |
|---|---|---|---|---|
â–¶Cardinals | -1.5 43%43% | O 1 50% | 30%30% | 30% Kalshi |
â–¶Reds | +1.5 57%57% | U 1 50% | 30%30% | 30% Kalshi |
St. Louis and Cincinnati close a four-game set at Great American Ball Park with the board at 51c St. Louis and 50c Cincinnati as of the evening of August 19, 2026, and Kalshi and Polymarket within a cent of each other on both sides. The Cardinals (65-63, 33-29 on the road) send Michael McGreevy and his 3.48 ERA against Brady Singer (5-11, 4.66) and a Reds club that is 61-66 and hitting .226 as a team, worst in MLB. The series is split 2-2 with three of the four games decided by one run, which is why a market with a clear paper edge is still pricing a coin flip.
St. Louis and Cincinnati have played four games in four days at Great American Ball Park and split them 2-2, with three of the four decided by a single run. Thursday's finale is priced accordingly: St. Louis at 51c and Cincinnati at 50c as of the evening of August 19, 2026, one of the tightest moneylines on the MLB board. First pitch is 12:40 PM ET. The Cardinals bring a 65-63 record and a 33-29 road mark into a park where the 61-66 Reds are 32-35, which is the rare case where the visiting team owns the better split on both sides of the ledger.
Cardinals vs Reds Market Context
The Cardinals vs Reds board has drawn $23.3K in lifetime volume across Kalshi and Polymarket, and it is lopsided: the Cincinnati moneyline carries $16.1K of that against $5.8K on the St. Louis side. That volume imbalance has produced no price edge. Kalshi and Polymarket have sat within a single cent of each other since the board opened, and the intraday snapshot series shows both sides oscillating between 50c and 51c without establishing a direction. A market that opens flat and stays flat on this much volume is telling you it has no read, and given the series to date that is the correct read.
The stakes are asymmetric even though the price is not. St. Louis sits third in the NL Central, 14 games behind Milwaukee (78-48), and three games out of the third National League wild card behind San Diego (68-60). Cincinnati is 17.5 back in the division and 6.5 out of that same wild card spot. The futures boards price the gap far more decisively than the game board does: the Cardinals playoff market trades at 12c while the Reds playoff market sits at 3c. For Cincinnati this is a spoiler game. For St. Louis it is a game they need to bank, and losing the finale of a series they led 2-1 after Tuesday would cost them a real slice of that 12c.
Head to head, the Cardinals hold the 2026 season series 7-5 through 12 games. The four games in this set have been decided by 1, 1, 3, and 1 runs: St. Louis won 2-1 and lost 6-5 in 10 innings in Monday's doubleheader, took Tuesday 3-0, and dropped Wednesday 5-4. That is a pick-em series producing pick-em results, and the board has stopped trying to separate them.
Cardinals vs Reds Pitching Matchup
Michael McGreevy (5-9, 3.48 ERA) starts for St. Louis against Brady Singer (5-11, 4.66 ERA) for Cincinnati. The 1.18-run ERA gap is the largest single edge either side has in this game, and it belongs to the road team. The rotations behind them match that: the Cardinals staff carries a 3.99 team ERA, 12th in MLB, against a 4.48 Reds mark that ranks 24th.
The offenses cut the other way, but not far enough to justify the price. Cincinnati is hitting .226 as a team, dead last in MLB at 30th, and has scored 509 runs, 27th. St. Louis is hitting .240 with 558 runs, 20th and 18th respectively. Neither lineup is good. One of them is the worst in baseball by batting average, and it is the team the market has installed as a coin flip at home.
The individual matchups are where Cincinnati earns its 50c. Sal Stewart has carried the Reds with 27 home runs and 94 RBI, and Elly De La Cruz leads the club at .259. St. Louis counters with Alec Burleson (.289, 92 RBI) and Jordan Walker (25 home runs). Cincinnati's power concentration is the argument for a lineup that cannot string hits together in a park that shortens the swing required to score. St. Louis has the more reliable defense behind its starter, with 54 errors (tied 5th fewest in MLB) against Cincinnati's 69 (20th).
The read: on starter, rotation, defense, road record, and season series, St. Louis has the better of it, and the board is giving the Cardinals a single cent for all of that. The 51c side is where the value sits, and Kalshi and Polymarket agree on the number so there is no platform to prefer.
A secondary Kalshi market on this game prices a run scoring in the first inning at 50c on $2.0K of volume. Against Singer's 4.66 ERA and McGreevy's 3.48, that is a market treating both starters as equally likely to be tagged early, which is a harder position to defend than the moneyline is.
When the Cardinals vs Reds Market Resolves
The moneyline resolves to the team that wins the game, scheduled for 12:40 PM ET on Thursday, August 20, 2026 at Great American Ball Park in Cincinnati. Contracts settle at $1 per share for the winning side and $0 for the losing side once the game is official and final. The first-inning market settles on whether either team scores in the top or bottom of the first. Kalshi and Polymarket both settle from the official final score, and a postponement or suspension pushes settlement to the completion date or voids per each platform's published rules. This board carries no spread or total, so the moneyline and the first-inning contract are the only lines to trade.
Key Cardinals vs Reds Catalysts
Starter gap: McGreevy's 3.48 ERA against Singer's 4.66 is the widest verified edge in the game and it sits with the 51c side.
Cincinnati's contact problem: a .226 team average ranks 30th in MLB, and the Reds have scored 509 runs on the season, 27th.
Series momentum is noise: the four games in this set were decided by 1, 1, 3, and 1 runs, so the 2-2 split carries no predictive signal either direction.
Wild card leverage: St. Louis is three games out of the third National League wild card, Cincinnati is 6.5 out, and the futures boards price that at 12c versus 3c.
A flat board: the moneyline has not left the 50c to 51c band since opening, and Kalshi and Polymarket have never diverged by more than a cent, so there is no line-movement story to trade against.
Getaway-day lineups: a 12:40 PM ET start after a four-game set is where rest days appear, and either manager resting a regular moves this price more than anything on paper does.
Related Cardinals vs Reds Markets
The season-long context for this game lives on the NL Central division market, where Milwaukee's 78-48 record has already pushed both of these clubs out of the picture, and on the two playoff boards linked above. For the previous game in this series, see Wednesday's Cardinals vs Reds board, which Cincinnati won 5-4. Full rosters, futures, and every remaining game for each club are on the St. Louis Cardinals hub and the Cincinnati Reds hub. The rest of Thursday's slate, with live Kalshi and Polymarket prices on every game, is on today's MLB board.
Resolution Criteria
The moneyline resolves to the team that wins the game, scheduled for 12:40 PM ET on Thursday, August 20, 2026 at Great American Ball Park in Cincinnati. Winning-side contracts pay $1 per share and losing-side contracts resolve to $0 once the game is official and final. The first-inning contract settles on whether a run scores in either half of the first inning. Kalshi and Polymarket both settle from the official MLB final score. If the game is postponed, it settles on the completion date under each platform's published rules; a suspended or canceled game that is never completed voids per platform policy. The board carries no spread or total market for this game.
Key Factors
- Michael McGreevy (5-9, 3.48 ERA) versus Brady Singer (5-11, 4.66 ERA), a 1.18-run starter edge to St. Louis
- Cincinnati's .226 team batting average ranks 30th in MLB and the Reds have scored 509 runs, 27th
- Series split 2-2 with three of four games decided by one run, so recent results carry no signal
- St. Louis is three games out of the third NL wild card at 12c to make the playoffs; Cincinnati is 6.5 out at 3c
- Moneyline has held a 50c to 51c band since opening with Kalshi and Polymarket never more than a cent apart
- Getaway-day 12:40 PM ET start after a four-game set raises the odds of rested regulars in either lineup
What are the current Cardinals vs Reds odds?
As of the evening of August 19, 2026, St. Louis is 51c and Cincinnati is 50c on the moneyline, with Kalshi and Polymarket both at those numbers. That is effectively a coin flip for a game with first pitch at 12:40 PM ET on August 20.
Who is favored in Cardinals vs Reds on August 20, 2026?
St. Louis is the nominal favorite at 51c, an implied 51% win probability, versus 50% for Cincinnati. The Cardinals are 65-63 with a 33-29 road record against a 61-66 Reds team that is 32-35 at home.
Where can I trade the Cardinals vs Reds market?
Both Kalshi and Polymarket list the moneyline, and the board has taken $23.3K in lifetime volume across the two platforms. Kalshi also lists a first-inning run market on this game at 50c with $2.0K traded.
Who are the probable starting pitchers?
Michael McGreevy (5-9, 3.48 ERA) starts for St. Louis and Brady Singer (5-11, 4.66 ERA) starts for Cincinnati. The Cardinals rotation carries a 3.99 team ERA, 12th in MLB, against a 4.48 Reds mark that ranks 24th.
When does the Cardinals vs Reds market resolve?
It settles when the game goes final on Thursday, August 20, 2026, first pitch 12:40 PM ET at Great American Ball Park. Winning contracts pay $1 per share.
What should I watch before this market resolves?
Lineup cards. A 12:40 PM ET getaway-day start after four games in four days is where regulars sit, and with the board frozen in a 50c to 51c band since opening, a scratched bat is the single most likely thing to move this price before first pitch.