Friday, January 29, 2010

The Best And Worst Days of The Week To Invest

I compiled the daily ups and downs of the S&P500 since the beginning of 2009. There have been reports circulating that Mondays are good days for the market, and that Fridays are bad days. So this study will shed some light on whether this is fact or fiction.

1. Number of positive days versus negative days:

2. Monday to Friday percentage of positive returns versus negative returns since March 15 2009 (same table as above, but in percentages):

2. Average daily returns since January 2 2009 and since March 15 2009:

So, since March 2009, clearly Mondays have been the best days of the week in terms of ROI (+0.35% on average), closely followed by Thursdays (+0.30%).

However, in terms of the best chance to get a positive day, that honor belongs to Thursdays, when 64.4% of the the time there were positive returns.

The worst day is Tuesdays, both in terms of ROI (average -0.03%, this on wildly positive period) and in terms of chances of losing money (47.8%).

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Deming said...

Saturday musings:

Certainly not looking to provide you with more work, but it would be interesting to see the impact of the first day of the month, especially if it falls on a Monday. For that matter, compare Monday first day of month to other days when they are first day of the month.

There's been talk of pension and mutual fund money flowing in around the first. Of course with mutuals, recent evidence reportedly has shown fund increases mainly in the fixed income offerings.

And if you really have time, you could look at a study of the start of the quarter as well as the end of the quarter?

Perhaps the The Trader's Almanac already has this information.

Have a nice weekend.


The Shocked Investor said...

Sure, here we go:

1st of the month since Jan 09: +0.09%

1st of the month since March 15 09: +0.59%

1st on the month by weekday, MON to FRI, since Mar 09:

+1.60% -0.49% +1.17% -2.48% +0.55%

There were 3 MONs, 2 TUEs, 2 WEDs, 1 THU, 1 FRI

Mondays 1st of the month look good. However, please note that June's was high at 2.4%.

Deming said...

Thank you!


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