Sell in May?

Is May really a good time to sell?

I looked at the past twenty-nine May trading periods on the NASDAQ -- from May 1980 to May 2008. Surprisingly, the NASDAQ closed higher during the month of May a very respectable 19 out 29 times -- a 66% occurrence rate.

Even more interesting, since the Dotcom bottom, the occurrence rate of a positive May close accelerated to 83%. The NASDAQ has posted gains in five of the past six May trading periods.

The result is that in the 29-year sample, the average NASDAQ performance in May was actually a gain of 1.82%.

So much for old wives' tales.

It's worth noting that, up or down, the average moves were statistically significant as well. During the years that the index moved up in May, the average gain was 4.99%. During the years the NASDAQ fell, the average May loss was -4.21%.

The SPX produced similar results. Since 1980, the SPX closed higher in May 20 out of 29 times -- one year better than the NASDAQ! The average SPX performance in May for the past 29 years has been a respectable gain of 1.38%.

The bottom line is that, on average, the market moves higher during most May trading periods. When it does, the moves tend to be a big ones as well. When the market moves lower in May, it's usually a hefty tumble.

Will the stock market close higher in May 2009? It's impossible to know, but a seasonal wives' tale isn't the place to look for answers.

Investing is so complex that there is a natural tendency to try and simplify the process. The problem with simplification is that, by its very nature, it distorts the data. In the case of salty trading yarns, this distortion can produce completely erroneous interpretations.

So maybe it's Sell in June?

The most reliable advice is probably the most useful epithet of them all:

Trade what you see, not what you think.

Good luck trading.

best

dk

NASDAQ Historical Performance in May
May 1980 -- 7.47%
May 1981 -- 3.11%
May 1982 -- (3.34%)
May 1983 -- 5.35
May 1984 -- (5.91%)
May 1985 -- 3.65%
May 1986 -- 4.41%
May 1987 -- (0.30%)
May 1988 -- (2.34%)
May 1989 -- 4.36%
May 1990 -- 9.26%
May 1991 -- 4.41%
May 1992 -- 1.15%
May 1993 -- 5.91%
May 1994 -- 0.18%
May 1995 -- 2.44%
May 1996 -- 4.44%
May 1997 -- 11.07%
May 1998 -- (4.80%)
May 1999 -- (2.84%)
May 2000 -- (11.91%)
May 2001 -- (0.27%)
May 2002 -- (4.30%)
May 2003 -- 8.99%
May 2004 -- 3.46%
May 2005 -- 7.63%
May 2006 -- (6.19%)
May 2007 -- 3.15%
May 2008 -- 4.55%

29-year avg = +1.82%