Back to 1900, from what I found, the s&p had four time periods where it was down five months in a row: 1937 1942 1946 1974 Not even 2002 However, the dow adds three time periods to this: 1966 1977 2002 So, at most, 7 times since 1900 has a major index gone down five months in a row. Thus, there is a 2.7% chance of us ending the month down? (257 five month periods over the last 1287 months?) My math is probably off, but it seems close. I am willing to take a lsmall long position on the next gap down and hold until end of month.