What’s the best strategy when investing cash, all at once or dripping in?

I'm often asked by those with money to invest that given the current market conditions whether it is best to invest all their money at once or whether to invest it in stages, known as dripping. If it's the latter then what is the optimum frequency i.e. monthly, quarterly or yearly.

It really is the million dollar question. A key aim of the research I publish for 80-20 Investor members is to attempt to answer these kinds of questions because they can positively influence investor returns for the rest of their DIY investing journey. So in this article I look at the returns produced by the FTSE 100 during key periods of its 30 year history.

The chart below shows the total return achieved if you had invested in the FTSE 100 since 1986  (which assumes that all dividends were reinvested):

You can get a feel for the ups and downs of the market over that time.