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system
who determines, and how, the composition of the s&p 500 index?
user
s & p's site has a methodology link that contains the following which may be of use: market capitalization. unadjusted market capitalization of us$ 4.6   billion or more for  the s&p 500, us$ 1.2 billion to us$ 5.1 billion   for the s&p midcap 400, and us$ 350  million to us$ 1.6 billion for   the s&p smallcap 600. the market cap of a potential  addition to an   index is looked at in the context of its short- and medium-term   historical  trends, as well as those of its industry. these ranges are   reviewed from time to time to  assure consistency with market   conditions.  liquidity. adequate liquidity and reasonable price – the   ratio of annual dollar value  traded to float adjusted market   capitalization should be 1.00 or greater, and the company  should   trade a minimum of 250,000 shares in each of the six months leading up   to the  evaluation date.  domicile. u.s. companies. for index purposes,   a u.s. company has the following  characteristics:  the final determination of domicile eligibility is made by the u.s.   index committee.
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