Trends/Relative strength, cycles and structure

Day-of-week effect

The stock's average return on each day of the week, over past years.

Relative strength, cycles and structureBest on 3Y, 5Y, MAXAlso called weekday returns
Day-of-week effect diagramIllustration of the day-of-week effect shape. It is a sketch, not real price data.Average return by weekdayMonTueWedThuFri
Illustration of the day-of-week effect shape. It is a sketch, not real price data.

What it shows

This groups daily returns by weekday. The bars show the average return for Monday through Friday.

Studies of the S&P 500 once reported differences between weekdays. They have been much smaller in recent decades. We show the stock's own record without claiming it will continue.

How we find it

The same code that draws it on your chart follows these steps, with the same result every time.

  1. Compute the daily return for every trading day.
  2. Group by weekday.
  3. Average each group.
  4. Show bars with the share of positive days.

Starting values: Years up to 10. These are proposed and will be tuned on real price data before launch.

How to read it

  • Each bar is one weekday.
  • Teal: positive average. Red: negative.
  • Differences are small.

Status labels you may see

LabelWhat it means
Best dayHighest average return.
Worst dayLowest average return.
No differenceSpread under 0.05%.

What cancels it

Nothing cancels it.

What traders check next

  • Standard deviation.
  • Sample size.
  • Changes over the years.

Limits

  • Differences can be by chance.
  • Effects shrink once known.
  • Holidays shift the calendar.

Try it in forecastviz

  • Open any ticker and choose Relative strength, cycles and structure → Day-of-week effect in the left menu.
  • Switch between 3Y, 5Y, MAX to see how the picture changes.
  • Compare with Monthly seasonality and Turn-of-month effect on the same chart.
Open on a ticker

Questions

Is the Monday effect real?

It was reported historically. Recent evidence is weak.

Can I use it?

We only describe the past.

Related trends

Monthly seasonalityTurn-of-month effectEarnings run-upDominant cycle

Further reading

  • O'Neil, How to Make Money in Stocks
  • Levy, The Relative Strength Concept of Common Stock Forecasting
  • Pring, Technical Analysis Explained
  • Frost and Prechter, Elliott Wave Principle
  • Hank Pruden, The Three Skills of Top Trading
  • Hirsch, Stock Trader's Almanac
← Monthly seasonalityTurn-of-month effect →

Educational only. Not financial advice, and not a price forecast. Charts are drawn by code from past price data, which may be delayed.