May 4th, 2002, 12:05 pm
You have to be careful about how the convertible bond gamma is defined.Normally, a high gamma would mean the underlying price is near the exercise price and there is not much time until expiration. That could certainly happen with a convertible bond near maturity.But it's rare for a convertible bond to get to maturity with the stock near the exercise price. It does happen, but it's more likely this is a bond that is on the borderline for being called. It might have a delta of, say, 0.7 if it is not called, and 1.0 if it is called (because it would be converted upon call). A small move in the underlying stock price might tip the issuer's decision and move the delta by 0.3.However, computing delta (hence gamma) for callable convertible bonds is not standardized. Different people do it different ways, and it is very sensitive to modelling assumptions.