Polymarket

Diamondbacks Stun Cubs 5-4, Delivering Major Upset in Polymarket Prediction Market

A high-stakes Polymarket prediction market saw a dramatic upset as the Arizona Diamondbacks rallied in the ninth inning to defeat the heavily favored Chicago Cubs 5-4, defying significant pre-game odds.

Admin

— 2 min read

PHOENIX, AZ – In a stunning turn of events on August 25, 2026, the Arizona Diamondbacks delivered a dramatic 5-4 victory over the Chicago Cubs, resolving a highly liquid Polymarket prediction market against overwhelming odds. The market, which accumulated a trading volume of $637,047, had priced the Chicago Cubs with an 86.6% implied probability of winning, while the Arizona Diamondbacks were given a mere 13.4% chance of victory before the game.

The market question focused on the outcome of the MLB game between the two teams, scheduled for 9:40 PM ET. Heading into the contest, the Chicago Cubs were enjoying a strong season, holding a 75-56 record and sitting second in the NL Central as of August 24. Their recent form against the Diamondbacks was also dominant, having won all three previous encounters in the 2026 season, including a decisive 7-0 shutout victory the day prior, on August 24. This strong performance likely contributed to the market's confident lean towards a Cubs win.

For much of the game, the market's strong conviction in the Cubs appeared justified. Chicago's starting pitcher, Clay Holmes, delivered a stellar performance, baffling Diamondbacks hitters through seven scoreless innings, allowing only two singles and two walks while striking out five. The Cubs built a comfortable 4-0 lead, with Ian Happ hitting a three-run homer in the fourth and Michael Busch adding an RBI single in the sixth.

However, the Diamondbacks, trailing 4-0 in the eighth, began a late-game surge. They scored three runs in the eighth inning against Cubs reliever Daniel Palencia, cutting the deficit to 4-3. The true drama unfolded in the bottom of the ninth. With the Cubs still clinging to a one-run lead, pinch-hitter Ryan Waldschmidt stepped to the plate with two outs and a runner on second. Waldschmidt launched a game-winning, two-run home run, stunning the Cubs and securing a dramatic 5-4 walk-off victory for Arizona. This pivotal win brought the Diamondbacks within one game of the San Diego Padres for the final National League wild-card spot.

The outcome serves as a stark reminder of the inherent unpredictability of sports, even when probabilistic markets suggest a clear favorite. Despite the Cubs' commanding pre-game odds and their dominant performance for most of the contest, the Diamondbacks' late-inning heroics completely flipped the script. For participants in the Polymarket, those who bet on the underdog Diamondbacks saw a significant return on their investment, while the vast majority who sided with the heavily favored Cubs faced a loss. This dramatic resolution highlights the high-risk, high-reward nature of prediction markets and the impact of unexpected game developments on market outcomes.

Sources:

Market data fetched at 2026-08-26 06:15 UTC | Polymarket ID: 3720883

This article is generated by AI for informational purposes only. It does not constitute financial advice. Always do your own research before making any investment decisions. Data sourced from Polymarket and public web sources.

Read more