Sector Average Index (SSAI)
To provide investors with a better measure of the UK equity market than
the FTSE 100, 350 and All Share indices.
The FTSE 100, 350 and All Share indices are all dominated by a small
number of multi-national companies with exceptionally high Market
Capitalisations e.g.:- HSBC, BP, Vodaphone, GlaxoSmithKline. With
the All Share Index 1% of the companies make up about 40% of the
Capitalisation! Furthermore these indices are dominated by a
small number of sectors.
While the FTSE 250 index does not suffer from domination of the largest
companies, shares from five sectors (out of 38) add up to 40% of the
250 e.g.:- Support Services, Real Estate, General Finance and General
The SIGnet Index is based on the unweighted average of the FTSE Sectors
Indices. Thus each of the indices has an equal influence
irrespective of its size. There are 38 in all with 2 excluded
because of insufficient companies – Forestry & Paper and Industrial
The FTSE Sector Indices, on which it is based, are themselves based on
the constituents of the FTSE All Share Index and thus exclude
Fledgling, AIM and PLUS companies.
It can be used for a basis against which to compare share and portfolio
performance. The FTSE 100 and All Share indices are commonly used
for this purpose. The SIGnet Index is currently more demanding
because the usual indices have been depressed by the dominating
companies. Its performance and that of the FTSE 250 compare
ShareScope calculate the SIGnet Index daily and include it in their
Indices Section. It is charted back to the beginning of
2000. The SIGweb site provides a quarterly chart of the SIGnet
index and the FTSE 100, 250, Scap, All Share, Fledgling and AIM All
Share indices. Also a monthly showing changes in values.