While the number of listings on the JSE has decreased steadily over the past 30 years, the number of unit trusts has proliferated. The JSE hosts just over 300 companies, with fewer than 100 realistically investible by fund managers.

This makes for tricky slicing and dicing — how many ways can you repackage 100 shares? One way is offshore investing, but stock picking outside a home market is usually a punishing exercise for a fund manager. In my view the most value is added (or subtracted) in the binary decision to either buy offshore or not...