Trustees are governed by legislation used to be called prudent investment guidelines-basically you could not have more than around 60% in equities around 10 % in property,5% in cash and balance in bonds as I recall.It follows the returns are much different to the returns of shares or property.You would tend to find this account would lag a bull market but beat a bear market-probably the right sort of thing to do with retirement money.Of course the salesman,administrator,investment manager,trustees,fsb and goverment all want their fees and this takes money out of account.It's even worse if death,disability and funeral insurance costs are taken off the investment money-this can make a big dent in the savings-I used to be in this business-if you know what you are doing and get the appropriate tax relief a provident fund can be a good security blanket for your old age(assuming you make it) but you will never get rich this way.