Price discovery during parallel stocks and options preopening: Information distortion and hints of manipulation

Abstract

Many exchanges act to prevent manipulative orders from distorting informative price discovery during stock and options’ markets preopening. Most preopening sessions run in parallel: indicative book-based stock prices alongside traded index options, whose underlying asset is the indicative index. Lead-lag patterns between the options-implied and the indicative indexes may point to differences in informational efficiency and/or manipulated prices. With three regulatory events throughout our sample, serving as natural experiments, we explore price discovery properties in both markets. We find significant lead-lag, price reversal, and order cancellation patterns similar to those predicted by theoretical models of manipulation, together with informational inefficiencies.