Do order flows in index derivatives play an informational role? Weekly index put order flow on the International Securities Exchange positively and robustly predicts weekly S&P 500 index returns. This result obtains mainly for net put buying and is stronger in high VIX periods and in periods...

We examine how informed traders trade in the option market around news announcements. We show that their profits depend on whether positions are long or short, whether trades take place before or after news releases, and whether events are scheduled or unscheduled. We predict and find that...

We train a machine learning method on a class of informed trades to develop a new measure of informed trading, the Informed Trading Intensity (``ITI''). ITI increases before earnings, M&A, and news announcements, and has implications for return reversal and asset pricing. ITI is effective...

We document a transaction level invariance relation among concurrent activity variables in the S&P 500 futures market: return volatility per transaction is proportional to the inverse of the squared expected trade size. It captures the time series behavior extremely well. Even more strikingly,...