Market Price

The market price on a Prediction Market is determined by continuous two-sided trading in the Order Book. Buyers submit bids and sellers submit asks; when a bid matches an ask, a trade executes and that transaction becomes the Last Price. Most platforms also display the Midpoint Price, computed as (best bid + best ask) / 2, as a neutral reference. Because event contracts settle at $1.00 or $0.00, the market price directly encodes Implied Probability. Platforms like Kalshi and Polymarket update displayed prices in real time as the Matching Engine processes incoming orders. During quiet trading periods the market price may lag true fair value if the most recent trade occurred long ago.

Seeing a market price of $0.65 does not guarantee you will buy at $0.65. A Market Order fills at the best available ask, which may be higher than the displayed midpoint, especially in markets with a wide Bid-Ask Spread. For large positions, Slippage pushes average fill prices further from the quoted market price as the order consumes multiple levels of the Order Book. A Limit Order lets you specify the exact price you are willing to pay, protecting you from adverse fills but risking non-execution if the market moves away. Understanding the difference between the quoted market price and your likely execution price is essential for accurate Expected Value calculations and realistic Mark-to-Market accounting.