Skip to main content

*Interactive Investor Offer: No platform fee for 1 year*


How much do you pay for your investment platform? Fancy a free one?
Simply click the link below, open up an ISA/SIPP/GIA then either fund £5k or transfer in from existing provider and you'll get the platform free for a year, saving potentially £360
Click here to save

Recent Posts

January 2026 update

Switching things up slightly from this month going forwards, nothing major, don't worry. I'm just swapping around the finance and non-finance update. Over the past couple of years, as my numbers have compounded the numbers have mattered less and the lifestyle has risen to a priority. 2 months off work, again! Regular readers will know that I took 8 weeks Unpaid Parental Leave in 2025, taking off pretty much all of the school holidays to spend time with my kids. In January I've submitted the same again, and just had it approved (not that they can't not approve it, they can delay it under extreme circumstances but can't turn it down outright - see more in a previous post of mine here ). Lots of plans this year, so far we have booked a 2 week driving holiday in the French Alps, a long weekend in Salzburg, a biking holiday and Efterling in the Netherlands as well as a few days in Wales and the Peak District. Snowy Scarborough We had a night booked in Scarborough right a...

What is the best day of the month to invest?

Person on phone: Of course sir, and what day would you like the direct debit to be set up for?
Me: Errrrrr............not really fussed, maybe the 1st?

Is this a common question you've had asked to you? If you're not living hand to mouth then it shouldn't make much difference what day a payment leaves your bank account right?

Right??

Wrong!

If you're like me and follow the "pay yourself first" approach, then you have set up a regular direct debit into a Stocks and Shares ISA. But what day of the month is the best to plonk your money into the market?

I've grabbed daily data from 4 major stock market indexes since 1984, and analysed the average for each day of the month over that period.

Here are the results:





Assessment:


  • It is no surprise that the 1st of the month is the day that has the consistently best returns (0.1958% to be precise)
  • The 20th is consistently the worst performing day
  • Looking at the chart, the best day to put money into the stock market would be the period of time with the longest run of days with a positive return. Which looks like 25th of each month, with a run of 13 days!

Day breakdown:


Day Average of Up/down
01 0.20%
02 0.11%
03 0.03%
04 0.03%
05 0.06%
06 0.02%
07 -0.04%
08 0.03%
09 -0.08%
10 -0.04%
11 0.02%
12 0.02%
13 0.06%
14 -0.01%
15 -0.01%
16 0.14%
17 0.02%
18 0.09%
19 -0.07%
20 -0.11%
21 0.01%
22 -0.04%
23 -0.04%
24 -0.02%
25 0.03%
26 0.07%
27 0.00%
28 0.07%
29 0.10%
30 0.02%
31 0.10%



I've taken this analysis one step further and used these percentage returns to simulate what a £10k payment into the market would look like over 30 days (recycling percentages earlier on in the month).


30 day simulation:



  • Inadvertently this looks spirograph-tastic!
  • Also surprisingly, it also suggests that the 21st of each month is the winner!
  • The reason behind this is that it starts at the lowest point of the month, and then goes on compounding day after day. Yes, it suffers losses but these come after the money has compounded up already.



Year long simulation:


My brain hurts now, I might do this later after a lie down!


Comments