End of the month
It's fairly standard practice to make regular investments, and review existing investments (e.g. AIM accounts) at the end of each calendar month. I do this, but I've noticed that, recently anyway, markets seem to have a habit of dipping around the middle of the month then rising at the month end, suggesting that the end of the month may not be the best time to make regular investments.
I wonder if this is just a passing phenomenon or whether there is a more general trend for markets to rise at month end. Fairly simple to research if the answer's not known already.
Daisy42