Like other indices managed by S&P Dow Jones Indices, but unlike indices such as the Russell 1000 which are strictly rule-based, the components of the S&P 500 index are selected by a committee. When considering the eligibility of a new addition, the committee assesses the company's merit using eight primary criteria: market capitalization, liquidity, domicile, public float, Global Industry Classification Standard and representation of the industries in the economy of the United States, financial viability, length of time publicly traded, and stock exchange. Over the past few years, there has been a decline in the number of S&P 500 companies with classified boards. Requirements to be added to the index include: