Lifted in toto from Bespoke Investment Group:
The S&P 500 is currently up 5.05% through the first six trading days of October. Going back to 1928, this ranks as the 8th best start to October (through first six days) for the index, and the best start since 1982. Below are all years in which the S&P 500 gained more than 4% through the first six days of October. For each year, we also include what the index did for the rest of the month. As shown, the average performance for the rest of the month is 0.08% (median 1.25%), with positive returns 7 out of 11 times. Not great, but not bad either.