The First Day Of Month Seasonality In The S&P 500 (Trading The First Day Of The Month)

Last Updated on August 26, 2021 by Oddmund Groette

We have previously written about the turn of the month effect:

The turn of the month includes both the end of the month and the first three trading days of the new month. Let’s look at only the first trading day of the month:

How does the first trading day of the month perform? In this article, we look at the first day of the month seasonality in the S&P 500. The first trading day of the month shows abnormal returns and thus hands us some nice trading opportunities.

The first trading day of the month

Let’s first define what the first trading day of the month is:

This has nothing to do with the calendar day. The first trading day of the month is exactly what it says: the first day of trading. If the first calendar day of the month is on a weekend or on a holiday, the first trading day of the month is not the first calendar day.

The return on the first trading day of the month

Let’s check the return from the close of the last trading day until the close of the first trading day of the month. This is the result in the SPY from inception to July 2021:

The best days were up until the GFC in 2008/09. The average return is 0.25% – significantly better than any random day which has risen 0.04%.

The average gain has been 0.18% since 2010, hence the strategy still has some energy left.

If we look further back we can see that the strategy didn’t work very well (GSPC – the S&P 500 cash index):

The gain from the close of the last trading day until the close of the first trading day is evenly divided between close to open and open to close. This is the return from the close until the open of the first trading day of the month:

The average gain is 0.12%.

And this is the first trading day of the month from open to the close:

The average gain per trade is 0.13% – thus the gains are evenly distributed from the close to the open, and from the open to the close of the first trading day. The “day trade gains” are far higher than on any random day.

We have in a previous article looked at the returns in the S&P 500 divided between the night/overnight session and the daytrading session:

The first trading day of the month effect can be improved

We have a Trading Edge based on the first trading day of the month effect that will be published sometime in 2021 or 2022 (buying on the close of the last day of the month and selling x days later):

Likewise, an overnight/night strategy holding from the close of the last trading day until the open of the new month will be published.

Conclusion about the first trading day of the month:

As you can see from the number, it can be profitable to trade around the first trading day of the month. The returns from the close of the last day until the close of the first day shoes abnormal returns, and so do the return from the open to the close of the first trading day.

 

Disclaimer: We are not financial advisors. Please do your own due diligence and investment research or consult a financial professional. All articles are our opinion – they are not suggestions to buy %%or sell any securities.