If each of your time steps is one week long, you are not modeling the stock price terribly well over a one-week time period, because you are saying that there are only two possible outcomes. John Hull

# Tag Archives: John Hull

## We concluded that you cannot rely on delta hedging…

We concluded that you cannot rely on delta hedging alone. It sounds simplistic to say that now, but back then, this was the sort of thing people were only just beginning to realize. John Hull

## The real challenge was to model all the interest…

The real challenge was to model all the interest rates simultaneously, so you could value something that depended not only on the three-month interest rate, but on other interest rates as well. John Hull

## The HoLee model was the first term structure model….

The HoLee model was the first term structure model. I remember reading their paper soon after it was published and as it was fairly different from many of the other papers that I had read, I had to read it quite a few times. I realized that it was a really important paper. John Hull

## When interest rates are high you want the average…

When interest rates are high you want the average direction in which interest rates are moving to be downward; when interest rates are low you want the average direction to be upward. John Hull

## We started giving presentations at practitioner…

We started giving presentations at practitioner conferences in 1986, and since then all of our derivatives research has been stimulated by contact with practitioners. John Hull

## There are challenges in terms of the measurement of…

There are challenges in terms of the measurement of VAR for what are known as nonlinear derivatives, where things like gamma and vega are important dimensions of the risk. John Hull

## I guess any simple idea that is really good will…

I guess any simple idea that is really good will catch on quickly. John Hull

## Our starting point then was trying to find a way…

Our starting point then was trying to find a way to incorporate mean reversion into the HoLee model. John Hull

## Alan White and I spent the next two or three…

Alan White and I spent the next two or three years working together on this. We developed what is known a stochastic volatility model. This is a model where the volatility as well as the underlying asset price moves around in an unpredictable way. John Hull