As in previous years, there are many small to medium-sized shares in the top 20 list of Top Performers. The reason: the sheer size of established, blue-chip companies does not allow them to show sustained strong growth. Smaller firms and those experiencing turnarounds often do exhibit sustained periods of strong earnings growth. Astute investors anticipate this and buy accordingly, which pushes these firms up the rankings.

Even the prospect of much improved earnings can result in big share price movements, especially in the mining sector. Take Afgold and Simmers in this year's top 10. Not so long ago these shares verged on extinction. But with new life and new prospects they have an army of loyal followers in the form of gold bugs who have bid the share prices up.

Only Edcon, Grindrod and Group 5 can be regarded as larger, more established companies in the top 20 and they are here because they're turnaround cases from a few years ago.

Large-cap stocks, with few exceptions, don't have particularly strong earnings growth. Investors buy them more for sustainability of earnings and dividends.

More small-cap stocks will be knocking on the door of the top 20 in the near future. AltX, the JSE's small-cap exchange, has successfully attracted new firms to its ranks. It has outperformed the JSE in index appreciation. Many recent additions, especially in IT and construction, have soared on the exchange. Once they've been around for five years, they'll be eligible for inclusion in Top Companies. But one AltX company, ISA Holdings (formerly Y3K Group), is already close to making the top 20.

Other small and mid caps to watch are Clientele (up from 93 to 49), Advtech from 91 to 50, Anbeeco from 251 to 71, ZCI from 170 to 76, Metorex from 173 to 83, Vestor from 274 to 87, Conduit from 248 to 98, Ventel from 238 to 102, Thabex 223 to 120 and Foneworx from 228 to 142.