The FTSE Small Cap index consists of companies too small to be included in either the FTSE 100 or FTSE 250 (which combine to form the FTSE 350) but big enough to be included in the FTSE All-Share index. The index currently comprises 260 companies and the market capitalisation of companies in this index varies between £30m and £320m.
In the US small-cap indices such as the Russell 2000 are a big business – dozens of funds (tracker or otherwise) follow the small-cap segment of the US market. Here in the UK, by contrast, small-cap investing is exclusively the preserve of actively managed funds – there are no small-cap index trackers in the UK and not one ETF or unit trust tracker follows the all-important FTSE Small Cap index or the FTSE Fledgling index, which tracks really small companies that aren't even big enough to make it into the FTSE Small Cap index.
