This study examines day-of-the-week effects using hourly values of the Dow Jones Industrial Average. We find that over the 1963–1983 period the weekend effect has sifted from characterizing active trading on Monday to characterizing the non-trading weekend. Over the early part of our sample period negative returns characterize each hour of trading on Monday, while the return from Friday close to Monday open is positive. In the most recent subperiod, Monday average hourly returns after noon are all positive and the weekend effect is due to negative average returns from Friday close to Monday open.

ABSTRACT This paper employs a new approach to study the effects of option trading on the behavior of underlying stock prices. Extant research compares distributional properties of the stock price at two points in time divided by an event in the option market that might affect price behavior. As an alternative, we examine the stock price adjustment to the release of quarterly earnings using samples of firms with and without listed options. We find the two samples exhibit different adjustment processes, with the nonoption firms requiring substantially more time to adjust.