Hey that was some ride yesterday, wasn't it?

I took a quick look at the market stats and my portfolio late in the morning. It brought a smile to my face. Green was the dominant color. Nearly everything I owned was sharply up. Oh happy day.

When I checked again late in the afternoon after the day's close... Awful. All that green had somehow turned to red. More bad news in the mortgage lending market had once again spilled out into the markets in general. All those nice gains, paper gains though they were, had vanished and then some.

The magnitude of the price swing taking place in such a little time period got me to thinking. I started wondering how yesterday stacked up against historical swings in prices.

Now what I mean here is how yesterday stacks up against days when the market swung wildly in a single trading day. I didn't want to consider days in which some really good, or really bad, news caused the markets to head off in one direction. What I was after was those days with the big swings both up and down - all within a single trading day.

Interestingly, I learned that yesterday's swing from big gain to big losses didn't rank very highly in historical terms. In fact, it didn't make the top 20.

Yesterday's price swings, measured as the percentage differences between the opening and closing prices of SPY and the intra-day high and low prices of SPY, weren't even in the top 150.