What Are The Worst Days To Trade Stocks?

Last Updated on November 22, 2022 by Oddmund Groette

One of the most important factors in becoming a good trader is to know when you should NOT trade. The art of when to do nothing and just sit on your hands is just as important as anything else. So, what are the worst days to trade stocks (when you should sit on your hands)?

Thursdays and Fridays are the worst days to trade stocks during the week. The worst trading days of the month for trading stocks are trading days number 13, 14, and 22, and the worst trading days of the year are 35, 121, 111, 193, and 56.

In order to backtest the worst days to trade stocks we need to make some trading rules. In this article, we’ll make three backtests: one where we look at weekdays, one where we look at the trading days of the month, and the final backtest is when we measure the performance of the trading days per year.

In the backtests we use the S&P 500 as a proxy for the stock market. For simplicity, we backtest the oldest ETF still trading: SPY. It started trading in 1993 and we backtest all the data all the way back to the first trading day.

What are the worst days to trade stocks? Weekdays

Let’s start by looking at weekdays: we look at the performance from the close of one trading day to the close of the next (separated by weekdays).

Mondays0.04%
Tuesdays0.08%
Wednesdays0.05%
Thursdays0.02%
Fridays0.02%

Thursdays and Fridays are the worst days to trade stocks during the week! Albeit the worst, both are still profitable because they benefit from the tailwind of the overnight edge:

Opposite, if you buy at the close of a Monday and sell at the close of a Tuesday, you would have made 0.08% per week from 1993 until today. Because of the profitable Tuesdays, we have developed a Turnaround Tuesday trading strategy.

What are the worst days to trade stocks? Trading days of the month

In the table below we have in chronological order the performance of each trading day of the month (not calendar day – which we think is pretty irrelevant).

Trading day #Avg % Profit/Loss
10.25%
20.07%
30.08%
40.06%
50.02%
6-0.05%
7-0.01%
8-0.05%
90.07%
100.06%
110.17%
120.17%
13-0.06%
14-0.11%
150.04%
160.04%
170%
180.07%
190.02%
200.06%
210.06%
22-0.09%
230.2%

The first trading day is the best (from the close of the last trading day to the close of the first trading day).

The worst trading days of the month to trade stocks are trading days number 13, 14, and 22.

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Backtested trading strategies

The latter is a little surprising because it’s at the end of the month (most of the time number 22 is the last trading day of the month) and historically the last few days of the month are pretty bullish for stocks.

A strategy called the turn of the month trading strategy is based on both the end and beginning of a month.

What are the worst days to trade stocks? Trading days of the year

There is a max of 253 trading days in a year. When we backtest all of them (max 29 per trading day for the period back to 1993) we find out that the five worst trading days are number 35, 121, 111, 193, and 56.

However, because of the small number of trades, we would take these results with a pinch of salt.

What are the worst days to trade stocks? Conclusion

The worst days to trade stocks are Thursdays and Fridays, and the following trading days of the month: 13, 14, and 22.

In our own trading, we rely on the results from the first two backtests. We are always reluctant to initiate trades on these two specific weekdays, and we are rarely happy if we get a signal on the second last trading day of the month.

These two effects seem to hold up pretty well during all times of the trading year. Thus, as a rule of thumb, we rarely trade on Thursdays and Fridays, and additionally, we try to avoid mid-month (trading days 13 and 14, and the last trading day of the month.

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