A put option is a financial contract that gives the holder the right to sell an asset at a specific price by (or at) a specific date. A put option can therefore provide its holder insurance against a large drop in the stock price. This makes the prices of put options an ideal source of information for a market-based measure of the probability of a firm’s default.
There is a close link between prices of equity options and the default probability of a firm. We show that in the presence of positive expected equity recovery, standard methods that assume zero equity recovery at default misestimate the option-implied default probability.