Prediction markets led by Polymarket and Kalshi continue to grow worldwide, with monthly trading volume expected to rise from $2.2 billion in 2025 to approximately $2.56 billion this year. In Japan, however, actual wagering is difficult because of gambling regulations, limiting participation.
The two leading prediction markets, Polymarket and Kalshi, are rapidly popularising a system in which wagers can be placed on virtually any event, including sports, politics, corporate developments, and crypto assets. Wagers are expressed as a choice between yes and no or among multiple options, with the prices of yes and no contracts indicating the market's implied probability. Recently, the markets have been gaining rapid mainstream acceptance through partnerships with institutions such as the New York Stock Exchange and with media organisations.
Direct participation from Japan is difficult because of gambling regulations, and although the markets can be viewed, actual wagering is generally prohibited. Accessing overseas websites is technically possible but carries legal risks, and may raise issues similar to those surrounding online casinos.
Prediction-market trading volume was approximately $2.2 billion in 2025, but some observers say it could reach roughly ten times that scale this year, with sports, politics, and crypto assets accounting for the bulk of trading. As the markets become increasingly linked to government and corporate developments, debate is growing over their Predictive Power, including whether they can outperform conventional opinion polls in areas such as election forecasting. At the same time, risks including insider trading, match-fixing, and ethical concerns have been highlighted, making future regulation and market design key issues.