John Hull
John Hull
challenge depended interest model rates value
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.
caps european interest known model rate time traders version
In the interest rate area, traders have for a long time used a version of what is known as Black's model for European bond options; another version of the same model for caps and floors; and yet another version of the same model for European swap options.
alan asset developed known model moves next price spent underlying volatility
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.
modeling possible saying steps stock terribly time
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.
fairly few model paper papers published quite realized soon term
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.
concerned conclusion far huge pricing volatility
Briefly speaking, our conclusion is that stochastic volatility does not make a huge difference as far as the pricing is concerned if you get the average volatility right. It makes a big difference as far as hedging is concerned.
cannot concluded delta people rely simplistic sort sounds
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.
I didn't become interested in derivatives until 1982, 1983.
concerns extreme issue likely measures mentioned using
One important measurement issue concerns the fat tails problem that I mentioned earlier. VAR is concerned with extreme outcomes. If the tails of the probability distributions we are using are too thin, our VAR measures are likely to be too low.
interest rates sort term type
The problem with interest rates are that you are not modeling a single number, you are modeling a whole term structure, so it is a sort of different type of problem.
branches center extreme parts pattern reached reflect shape zero
Yes, our tree has an interesting shape. The center branches reflect the shape of the zero curve. When extreme parts of the tree are reached the branching pattern changes to accommodate the mean reversion.
led rates
Our research led on to other things, such as the fact that exchange rates are not lognormally distributed.
I think VAR is a very healthy development within the industry.
trying
Our starting point then was trying to find a way to incorporate mean reversion into the HoLee model.