According to the theory of efficient markets, the stock price on a competitive market is the best estimate of the present value of stock. This is the basic assumption for predictions using experimental markets.
The first part of the paper describes the features of such an experimental market, discusses shortly its advantages in providing predictions as compared to the traditional opinion polls and identifies some assumptions that can influence its efficiency and predictive accuracy. The second part of the paper dwells in the results of the first experimental market organized in the Czech Republic and the political stock market on the Czech parliamentary elections into the Chamber of Deputies in June 2002.