Background Note | HBS Case Collection | January 2008

Equity Derivatives

by Joshua Coval and Erik Stafford

Abstract

The goal of these simulations is to understand the dynamic replication technique behind the Black-Scholes/Merton options model. The simulations focus on a single stock and a risk-free discount bond, which are used to replicate a contingent payoff. The underlying stock and bond prices are randomly generated from the assumptions of the model, so that this simulation is testing the student's understanding and ability to use the model, rather than testing whether the model accurately explains prices. In each of the four simulations that make up this lesson, students are trying to replicate a contingent payoff, which is specified in terms of the closing stock price in one month (European-style derivative). The students are essentially working on an equity derivatives desk at a large bank and are responsible for delivering a derivative payoff to a client. The desk has taken in a premium upfront for guaranteeing the contingent payoff in one month's time. In the Black-Scholes/Merton model, a trader should be able to exactly match the contractual payment at expiration. Therefore, students are penalized based on the absolute difference between their actual ending value and a target ending value (starting value + derivative payoff). In particular, this difference is cumulated across all four simulations and then subtracted from their account.

Keywords: Equity; Bonds; Stocks; Price; Risk Management;

Citation:

Coval, Joshua, and Erik Stafford. "Equity Derivatives." Harvard Business School Background Note 208-117, January 2008.