January has quite a reputation on Wall Street as an influx of cash from yearend bonuses and annual allocations has historically propelled stocks higher. January ranks #1 for NASDAQ (since 1971), but fifth on the S&P 500 and sixth for DJIA since 1950. January is the last month of the best three-month span and holds a full docket of indicators and seasonalities.
DJIA and S&P rankings did slip from 2000 to 2016 as both indices suffered losses in ten of those seventeen Januarys with three in a row, 2008, 2009 and 2010 and then again in 2014 to 2016. January 2009 has the dubious honor of being the worst January on record for DJIA (-8.8%) and S&P 500 (-8.6%) since 1901 and 1931 respectively. The early stages of the Covid-19 pandemic mostly spoiled January in 2020 as DJIA, S&P 500, Russell 1000 and Russell 2000 all suffered declines. Only NASDAQ was positive.
In post-election years, Januarys have been modestly weaker. DJIA and S&P 500 slip to number #7 and #6 respectively but do maintain positive average performance. NASDAQ holds the outright best ranking of the five at 5th place, but the frequency of gains has historically been mixed. DJIA, S&P 500 and NASDAQ have all advanced in seven of the last nine post-election year Januarys. The two down post-election years since 1985 were 2005 and 2009.