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.