The ICB uses a system of 11 industries, partitioned into 20 supersectors, which are further divided into 45 sectors, which then contain 173 subsectors.
[1][2] The ICB is used globally (though not universally) to divide the market into increasingly specific categories, allowing investors to compare industry trends between well-defined subsectors.
The ICB replaced the legacy FTSE and Dow Jones classification systems on 3 January 2006, and is used today by the NASDAQ, NYSE and several other markets around the globe.
[3] Dow Jones divested itself of its 50% interest in the ICB in 2011 and announced it was creating its own version of it.
[4] Source:[5] Per the FTSE Global Total Cap Index, Information Technology is the biggest sector, with 25% of world capitalisation.