Abstract: An option provides a bundle of economic characteristics, including leverage, exposure to the underlying asset, exposure to a particular dynamic trading strategy, and exposure to volatility and jumps. The wide variety of traded options permits investors to choose particular economic characteristics. We group exchange-traded equity options into delta- and maturity-based buckets, which provide differential exposure to these economic characteristics. We examine the determinants of volume, signed volume, open interest, and gamma volume for these buckets. Option activity is concentrated in out-of-the-money and at-the-money options.Equity option activity is aetched strongly by volume in the underlying as-set, earnings announcements and dividend payments. Earnings announcements in particular generate substantial increases in volume in near determinate the-money and out-of-the-money options, no increase in open interest,and small additional negative gamma exposure for market-makers. Examination around earnings announcements of option trading by investor categories ands that small customers are likely to be option buyers, with large customers and rms supplying written options.