Calculating the optimal hedge ratio: constant, time varying and the Kalman Filter approach

A crucial input in the hedging of risk is the optimal hedge ratio - defined by the relationship between the price of the spot instrument and that of the hedging instrument. Since it has been shown that the expected relationship between economic or financial variables may be better captured by a time varying parameter model rather than a fixed coefficient model, the optimal hedge ratio, therefore, can be one that is time varying rather than constant. This study suggests and demonstrates the use of the Kalman Filter approach for estimating time varying hedge ratio - a procedure that is statistically more efficient and with better forecasting properties.