Information, trading, and volatility

We examine the effects of trading and information flows on the short-run behavior of stock prices by comparing the behavior of stock return volatility during trading and nontrading periods. We define nontrading periods as periods when exchanges and businesses are open but traders endogenously choose not to trade. After correcting for the bid/ask bounce and stickiness in quotes, we find that a large proportion of daily stock return volatility occurs without trades, especially for large firms. Furthermore, we provide new evidence that public (versus private) information is the major source of short-term return volatility.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31397/1/0000312.pd

Foundations of Multinational Financial Management

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The Behavior of Option Price around Large Block Transactions in the Underlying Security.

This paper investigates the behavior of stock and option prices around block trades in stocks. The results indicate that for both uptick and downtick block trades the stock prices adjust within a fifteen minute period after the block trade. Moreover, for uptick blocks there is no evidence of any stock price reaction before the block trade. However, the adjustment of stock price for downtick blocks begins about fifteen minutes before the block trade. They also find that option price behavior differs considerably from stock price behavior. Specifically, the authors' results suggest that options exhibit abnormal price behavior starting thirty minutes before the block and ending one hour after the block. The pattern is more pronounced for downtick blocks and for put options. The authors interpret this abnormal price behavior of options before the block trade as consistent with intermarket frontrunning. Copyright 1992 by American Finance Association.

The Allocation of Informed Trading across Related Markets: An Analysis of the Impact of Changes in Equity-Option Margin Requirements.

The authors examine the impact of changes in equity-option margin requirements on the liquidity of options and underlying stock markets. They find that the decrease in margin was associated with an increase in spreads and trade informativeness, and a decrease in depth for the underlying stocks. In contrast, option spreads decreased indicating a change in the relative allocation of informed traders between the two markets. When the required margin was increased, no significant change was observed in the underlying stocks but option spreads increased. Overall, the authors' results indicate that uninformed traders are more sensitive to the margin dimension of trading costs. Copyright 1995 by American Finance Association.