November 23, 2011
The paper presents three pieces of evidence that the inventory risk faced by market-makers has a primary effect on option prices. First, I introduce a simple method for decomposing the price impact of trades into inventory-risk and asymmetric-information components. The components are inferred from the difference between price responses of the market-maker who receives a trade and those who do not. Both price impact components are significant for option trades, but the inventory-risk component is larger.