How is the weight of SP500 sectors calculated?

[novicetrader69]

Said that there is going to be some shuffling around of companies in SP500 sectors, how is the weight of sectors calculated?

http://siblisresearch.com/data/sp-500-sector-weightings/

Is it simply based on the number of companies belonging to each sector, is it based on the volumes or the volumes times the price?

Thanks
nt

 

[jharmon]

Lots of GICS changes happening soon. Of course all of these weightings are crap because they haven't/won't be recalculated according to the new classifications, so historically they are inconsistent and meaningless in comparison to newer data.

The weighting of each company in the index is based upon it's market cap and its Investibility Weight Factor.

To determine sector weightings you group by the GICS sector and sum the weights of each stock.
https://us.spindices.com/documents/methodologies/methodology-index-math.pdf