The Day-of-Week Effect in Forex, Tested
Monday is supposed to be sluggish and best skipped; Friday is supposed to be unpredictable because positions are being closed. We measured daily ranges by day of the week across twelve pairs and checked both claims.
Day-of-week effect: what exactly was measured
The median daily range in pips for each weekday, separately for each of twelve pairs, over two years of daily data. The median rather than the mean, so that individual events do not distort the picture. One technical detail without which the result would be wrong: timestamps in the source data sit at 23:00 UTC and belong to the following trading day — without correcting for that shift, Friday bars land on Sunday and the whole calculation falls apart.
The numbers
Median daily range across 12 pairs, relative to Wednesday set at 100%:
- Monday: 99% of Wednesday's range
- Tuesday: 102% of Wednesday's range
- Wednesday: 100% of Wednesday's range
- Thursday: 105% of Wednesday's range
- Friday: 102% of Wednesday's range
The spread between the widest and narrowest day within a single pair ranges from 8 to 20 percent. For comparison, the difference between a calm and an active day within the same week is routinely twofold.
The folklore did not survive
Monday is not systematically quiet: for most pairs it sits in the middle of the distribution, and for some it is among the widest days. Friday is not systematically wild either. More tellingly, the narrowest day falls on different weekdays for different pairs, which would be odd for a stable calendar effect. The one weak regularity is that Thursday was most often the widest day — and even that rests on a difference of a few percent.
What to do with this
There is no basis for building a trading decision on the day of the week. Skipping Mondays would cut the number of trades by roughly a fifth without improving expectancy. The day's release calendar says far more about the coming range than the day's position in the week does.
Sample: daily quotes for 12 pairs over two years; method in how we run backtests.
This material is educational and is not individual investment advice. Backtested results do not guarantee similar results in the future. Trading forex carries the risk of losing capital.
Frequently asked questions
Is the forex market really quiet on Mondays?
Not according to our data. Monday's median daily range does not stand out, and for several pairs it was among the widest days of the week.
Should I avoid trading on Fridays?
The measurement gives no basis for such a rule. Friday ranges do not stand out systematically, and skipping a weekday cuts your sample of trades by about 20% without improving expectancy.
Is there any day-of-week effect in forex at all?
Across twelve pairs over two years the spread between weekdays is a few percent and is not consistent between pairs — too small and too inconsistent to build rules on.
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