The FTSE All-Share Index was originally called the FT Actuaries.

The FTSE All-Share Index represents the performance of all eligible companies listed on the London Stock Exchange’s main market, which pass screening for size and liquidity. The index captures 98% of the UK’s market capitalisation

FTSE All-Share Index is the aggregation of the FTSE 100 Index, FTSE 250 Index and FTSE SmallCap Index.

It’s top ten holdings make up 31% of the index.

HSBC Holdings 4.89%
British American Tobacco  3.70 %
GlaxoSmithKline 3.56%
BP 3.49%
Royal Dutch Shell A  3.05%
Vodafone Group 3.03%
AstraZeneca 2.89%
Diageo 2.42 %
Lloyds Banking Group 2.13&
BT Group 40,578 2.07%

[http://www.shareshop.hsbc.co.uk/shareshop/security.cgi?csi=50100]