I am noticing that the implied volatility of the S&P 100 is below 20% right now, which is the lowest it has been since when the financial crisis really picked up steam (September 2008). At the peak of the economic crisis this was around 80%.
The concept of portfolio insurance is simple – buying put options represents a form of insurance. You can play with these options and come up with some concepts that can be translated into English for less financially sophisticated people.
Let’s pretend you owned $100 of the S&P 500. If you wanted to insure your portfolio against any further downside for the rest of 2010 (i.e. you wanted to guarantee that you could sell your $100 of S&P 500 for $100 at the end of 2010), how much would it cost you? The answer is about $9.89 given closing option prices on December 24, 2009. This sort of insurance is good if you anticipate a possibility of the market declining, but you still want some “skin in the game” in the event the S&P 500 goes up between now and the end of the year.
We can repeat the same thought experiment, except asking ourselves if we wanted the right to sell your $100 of S&P500 for $90 by the end of 2010, a 10% loss. This insurance will cost you $6.14 to purchase.
The difference between these two values are $3.75.
What this practically means is you can bet the following ways (again, note I am indexing the value of the S&P 500 right now to 100 for the purposes of this post):
1. You can bet that the S&P 500 will not drop at the end of 2010. Reward for getting this right: $9.89 for $100 notional risk. Punishment for getting it wrong: $9.89 minus $1 for every $1 that the S&P goes below $100 at the end of 2010.
2. You can bet that the S&P 500 will not drop more than 10% at the end of 2010. Reward for getting this right: $6.14 for $100 notional risk. Punishment for getting it wrong: $1 for every $1 that the S&P goes below $90 at the end of 2010.
The “bets” to describe the results of predicting an S&P 500 level of 90 to 100 are a little more complicated to explain, but they can be done with portfolio insurance as well. Essentially you can feed any probability distribution into a model and have it crank out the optimal purchases/sales of options to correspond with your crystal ball forecasting.
Since I can’t forecast indexes, I’ll leave this to the gamblers. That’s what most option markets end up being. Right now, the option markets are saying that they expect volatility to be low, which keeps option prices low. This generally favours people that have strong beliefs that the markets will go rapidly in one direction or another.