Multi-Outcome Prediction Markets and Why the Odds Don't Add Up to 100%

Multi-outcome prediction markets split one question into multiple Yes/No rows, each priced separately, so adding the “Yes” prices often won’t equal 100 cents. That’s not automatically a mistake because the arithmetic depends on how the rows relate. In markets with only one winner, once one row resolves Yes, all others resolve No, so the Yes prices should total roughly 100 cents plus a small cost. In price-target ladders where multiple outcomes can win, totals can exceed 100 without error; investors should instead check ordering so higher targets never cost less than lower ones.