The EU's Exchange Trading System (EU ETS) dominated international activity in allowance-based markets. London is central to the EU scheme as ECX (European Climate Exchange) CFI contracts, which are traded on the ICE Futures exchange in London, made up 82% of trading on the EU ETS in 2006. The UK is also the leading investor in project-based transactions accounting for 50% of such investments in 2006, reflecting the large number of purchases made by financial institutions in central London.