Scottish Oriental Smaller Cos Trust plc SST

This investment trust invests in small-cap firms listed on Asian stock markets, excluding Japan and not including Australasia.

I’ve taken a look at a few of the small cap trusts and I don’t understand why the return of a £10k investment in a favourable scenario actually has a decreasing return from 1 to 3 to 5 years.

Sorry I’m new to this but I don’t get why they are recommended to hold for 5 years if it appears the returns are worse the longer you hold?