 Okay, folks, this is Chapter 3 and we're going to look at Gamma in this chapter. So we're looking at the spiders here and the markets have just closed about an hour ago, so you don't see the prices moving like we did earlier. But what I've done is I've pulled up the spiders and we're looking at the May 2012 options which has about 60 days to expiry. And also you can see that the spiders have closed at $140.85. I've also listed two columns here, one is the Delta and one is the Gamma. And in this chapter we're going to look at Gamma. The best way to understand Gamma, Gamma is a little tricky to understand because it's the second derivative of price. Gamma also defined as the rate of change of Delta. So it's a little tricky, so what I would do is I'm going to just focus on calls because puts can make it a little bit harder to understand because of the negative sign involved in the puts. What we'll do is we'll just focus on the calls and understand the concept of Gamma. The concept of Gamma works the same whether it is calls or puts. So once you've understood the concept here, you can certainly translate that knowledge onto the puts side as well. So let's focus on the calls side and try to understand Gamma. Gamma is defined as the rate of change of Delta. So what we mean by that? Now, we saw that the at the money options, for example, the 141 call is still the at the money option.