by Bill McBride on 8/08/2011 04:03:00 PM

From CNBC: Dow Skids 600, Worst Day Since Credit Crisis

The S&P 500 and the tech-heavy Nasdaq were down 6 percent. August is already on track to be the worst month for both indexes since Oct. 2008.

The CBOE Volatility Index, widely considered the best gauge of fear in the market, spiked above 40 to touch its highest level since Mar. 2009.

All 10 S&P sectors were lower, led by banks, energy and materials. Financials have plunged more than 20 percent this year.

Graph from Doug Short.

Click on graph for larger image.

Here is a table of the largest one day declines (in percentage terms) for the S&P 500 since January 1950. There were quite a few large down days in 2008 and early 2009 ... and now two in the last week (both in red).

Largest S&P 500 One Day Percentage Declines since 1950
	Date	Percent Decline	Close	Previous Close	Six Months Later
1	10/19/1987	-20.5%	224.84	282.70	15.3%
2	10/15/2008	-9.0%	907.84	998.01	-4.7%
3	12/1/2008	-8.9%	816.21	896.24	15.7%
4	9/29/2008	-8.8%	1106.42	1213.27	-28.8%
5	10/26/1987	-8.3%	227.67	248.22	15.3%
6	10/9/2008	-7.6%	909.92	984.94	-5.9%
7	10/27/1997	-6.9%	876.99	941.64	23.7%
8	8/31/1998	-6.8%	957.28	1027.14	28.0%
9	1/8/1988	-6.8%	243.40	261.07	11.7%
10	11/20/2008	-6.7%	752.44	806.58	17.9%
11	5/28/1962	-6.7%	55.50	59.47	10.6%
12	8/8/2011	-6.7%	1,119.47	1199.38	---
13	9/26/1955	-6.6%	42.61	45.63	14.1%
14	10/13/1989	-6.1%	333.65	355.39	3.2%
15	11/19/2008	-6.1%	806.58	859.12	10.1%
16	10/22/2008	-6.1%	896.78	955.05	-5.0%
17	4/14/2000	-5.8%	1356.56	1440.51	-2.0%
18	10/7/2008	-5.7%	996.23	1056.89	-18.1%
19	6/26/1950	-5.4%	18.11	19.14	10.0%
20	1/20/2009	-5.3%	805.22	850.12	18.1%
21	11/5/2008	-5.3%	952.77	1005.75	-4.8%
22	11/12/2008	-5.2%	852.30	898.95	4.8%
23	10/16/1987	-5.2%	282.70	298.08	-8.1%
24	11/6/2008	-5.0%	904.88	952.77	2.7%
25	9/17/2001	-4.9%	1038.77	1092.54	12.2%
26	2/10/2009	-4.9%	827.16	869.89	21.8%
27	9/11/1986	-4.8%	235.18	247.06	23.4%
28	8/4/2011	-4.8%	1200.07	1260.34	---
29	9/17/2008	-4.7%	1156.39	1213.60	-31.3%
30	9/15/2008	-4.7%	1192.70	1251.70	-36.8%
31	3/2/2009	-4.7%	700.82	735.09	47.1%
32	2/17/2009	-4.6%	789.17	826.84	27.2%
33	4/14/1988	-4.4%	259.75	271.58	7.0%
34	3/12/2001	-4.3%	1180.16	1233.42	-8.0%
35	4/20/2009	-4.3%	832.39	869.60	31.7%
36	3/5/2009	-4.3%	682.55	712.87	46.2%
37	11/30/1987	-4.2%	230.30	240.34	10.0%
38	11/14/2008	-4.2%	873.29	911.29	4.2%
39	9/3/2002	-4.2%	878.02	916.07	-6.4%
40	10/2/2008	-4.0%	1114.28	1161.06	-25.1%
41	10/25/1982	-4.0%	133.32	138.83	20.3%