The real fear index!
Now that today's plunge is being attributed to a single sell call on WFC from a single analyst, you can see how jittery the money in the market is.
My guess is that the drop in WFC triggered a switch in someones trading program, (probably GS) , and the rest of the market reacted to the sudden volume on the sell side.
The fear is definately there my friends and you can see it wouldn't take much of a spark to light the fuse.
At least one thing that we now know is that at least that 1 program trader is nervous about financials.