This study considers the problem of a price-setting monopolistic market-maker in a dealership market where the stochastic demand and supply are depicted by price-dependent Poisson processes [following Garman (1976)]. The crux of the analysis is the dependence of the bid-ask prices on the market-maker's stock inventory position. We derive the optimal policy and its characteristics and compare it to Garman's. The results are shown to be consistent with some conjectures and observed phenomena, like the existence of a ‘preferred’ inventory position and the downward monotonicity of the bid-ask prices. For linear demand and supply functions we derive the behavior of the bid-ask spread and show that the transaction-to-transaction price behavior is intertemporally dependent. However, we prove that it is impossible to make a profit on this price dependence by trading against the market-maker. Thus, in this situation, serially dependent price-changes are consistent with the market efficiency hypothesis.

We study the joint effect of the trading mechanism and the time at which transactions take place on the behavior of stock returns using data from Japan. The Tokyo Stock Exchange employs a periodic clearing procedure twice a day, at the opening of both the morning and the afternoon sessions. This enables us to discern the effect of the clearing mechanism from the effect of the overnight trading halt. While the periodic clearing at the beginning of the trading day is noisy and inefficient, the midday clearing transaction appears to be no worse than the two closing transactions.

The effects of asset liquidity on expected returns for assets with infinite maturities (stocks) are examined for bonds (Treasury notes and bills with matched maturities of less than 6 months). The yield to maturity is higher on notes, which have lower liquidity. The yield differential between notes and bills is a decreasing and convex function of the time to maturity. The results provide a robust confirmation of the liquidity effect in asset pricing.

Merton's [26] recent extension of the CAPM proposed that asset returns are an increasing function of their beta risk, residual risk, and size and a decreasing function of the public availability of information about them. Associating the latter with asset liquidity and following Amihud and Mendelson's [2] proposition that asset returns increase with their illiquidity (measured by the bid-ask spread), we jointly estimate the effects of these four factors on stock returns.

Merton's [26] recent extension of the CAPM proposed that asset returns are an increasing function of their beta risk, residual risk, and size and a decreasing function of the public availability of information about them. Associating the latter with asset liquidity and following Amihud and Mendelson's [2] proposition that asset returns increase with their illiquidity (measured by the bid‐ask spread), we jointly estimate the effects of these four factors on stock returns.

This paper examines the effects of the mechanism by which securities are traded on their price behavior. We compare the behavior of open‐to‐open and close‐to‐close returns on NYSE stocks, given the differences in execution methods applied in the opening and closing transactions. Opening returns are found to exhibit greater dispersion, greater deviations from normality and a more negative and significant autocorrelation pattern than closing returns. We study the effects of the bid‐ask spread and the price‐adjustment process on the estimated return variances and covariances and discuss the associated biases. We conclude that the trading mechanism has a significant effect on stock price behavior.

Merton (1987) proposes that an increase in a firm's investor base increases the firm's value. In Japan, companies can reduce their stock's minimum trading unit—the number of shares in a “round lot”—which facilitates trading in the stock by small investors. We find that a reduction in the minimum trading unit greatly increases a firm's base of individual investors and its stock liquidity, and is associated with a significant increase in the stock price. Further, the stock price appreciation is positively related to an increase in the number of shareholders.