The author analyzes the demand for shares and attempts to determine its influence on the liquidity of the Warsaw Stock Exchange. The analysis was conducted by calculating and bringing together values of key importance to the liquidity of the market and investment activity on the Polish stock market. The analysis showed that the liquidity of the Polish stock market decreased in the analyzed period (1995-2005). First, there was a drop in the value of stock trades in relation to the market’s capitalization. Subsequently, there was a problem involving the substantial concentration of trade on the exchange. On the basis of this situation, attempts were made to check the demand side of the stock market, especially in the institutional investor segment. Analyses conducted by the author indicate that, as a result of a dynamic increase in pension and investment fund assets in 2000-2005, these institutions substantially increased the value of shares in their possession, withdrawing some of the stock from “active” turnover. Over the next few years, more than 40% of the assets invested by these institutions in stock were tied up in the portfolios of open-ended pension funds. However, in the years that followed, assets held by institutional investors were subject to decreased turnover. This seems to indicate that institutional investors could pose a threat to the market’s liquidity by channeling substantial assets to the domestic stock market in a situation in which the supply of shares was insufficient. However, a supplementary examination of the average turnover in WSE-listed shares, particularly those making up the market’s free float, revealed that the activity of institutional investors, though decreasing with each passing year, was several times higher than average investment activity on the stock market. In other words, transactions made by institutional investors were the key driving force behind the market’s liquidity in the analyzed period. Unfortunately, the positive influence of institutional investors decreased in 2003-2005, a period that saw a major increase in pension and investment fund assets. The insufficient—and continually decreasing—liquidity of the stock market, coupled with the dynamic development of the institutional investor segment, particularly pension funds, justifies worries over the liquidity and stable development of the Polish stock market.