S&P 500

S&P 500
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Name	S&P 500
Type	Stock market index
Provider	Standard & Poor's
Introduced	1957
Components	500 large-cap companies
Market cap	Market-capitalization weighted
Homepage	Standard & Poor's

S&P 500 The S&P 500 is a widely followed stock market index representing 500 leading publicly traded companies in the United States. It is maintained by Standard & Poor's and is used by investors, fund managers, and policymakers as a benchmark for large-cap U.S. equities. Market participants including Vanguard, BlackRock, Fidelity, and State Street use it as the basis for index funds and exchange-traded funds such as those offered by Charles Schwab and Invesco.

History

The index traces institutional antecedents to the work of Henry Varnum Poor and publications associated with Standard & Poor's Financial Services LLC and was formally introduced in 1957 during a period of postwar expansion that included firms like General Electric, AT&T, ExxonMobil, and General Motors. Its evolution paralleled milestones such as the deregulation linked to the Kennedy administration and the financial innovations of the 1970s oil crisis, while episodes like the Black Monday (1987) crash and the Financial crisis of 2007–2008 shaped index governance and risk disclosure. Regulatory and market changes involving the Securities and Exchange Commission, New York Stock Exchange, and NASDAQ influenced component selection rules and corporate actions, with later technology-driven shifts highlighted by companies such as Apple Inc., Microsoft, Amazon (company), and Alphabet Inc. joining the index.

Composition and Constituents

Constituent selection is overseen by a committee at Standard & Poor's that evaluates companies across sectors represented in classification systems like the Global Industry Classification Standard and allocates seats among industries including firms such as Johnson & Johnson, JPMorgan Chase, Pfizer, and Berkshire Hathaway. Eligibility typically requires listing on exchanges such as the New York Stock Exchange or NASDAQ, minimum liquidity thresholds frequently met by conglomerates like Walmart and Procter & Gamble, and domicile considerations that affect inclusion of multinational corporations like Alibaba Group or Toyota Motor. Revisions occur when companies merge, are acquired by firms like Berkshire Hathaway or Johnson & Johnson, or undergo corporate actions involving entities such as Cisco Systems or Intel Corporation.

Calculation and Methodology

The index is calculated using a market-capitalization weighting scheme that aggregates free-float market values of constituents and applies a divisor to maintain continuity during corporate events; similar weighting methodologies are used by index providers like MSCI Inc. and FTSE Russell. Inputs include share counts reported in filings with the Securities and Exchange Commission and price data from exchanges including the New York Stock Exchange and NASDAQ Stock Market. Adjustments for stock splits, spin-offs, dividends, and mergers—events exemplified by transactions involving AT&T Inc., Pfizer Inc., and 3M Company—require divisor recalibration to preserve index continuity during corporate restructurings adjudicated under standards influenced by Financial Accounting Standards Board pronouncements.

Market Role and Economic Significance

The index serves as a benchmark for institutional portfolios managed by firms such as BlackRock, Inc., Vanguard Group, and State Street Corporation, and underpins passive investment vehicles like the SPDR family created by State Street Global Advisors. Policymakers at the Federal Reserve and analysts at research organizations such as Moody's Corporation and Goldman Sachs monitor it for signals about market confidence during events like the COVID-19 pandemic market shock and macroeconomic episodes tied to the Federal Reserve System’s rate decisions. Its performance influences corporate financing decisions at firms like Tesla, Inc. and Nike, Inc. and is tracked by media outlets including The Wall Street Journal, Financial Times, and Bloomberg L.P..

Performance and Returns

Long-term total return on the index incorporates capital appreciation plus reinvested dividends from companies such as Coca-Cola Company, McDonald's Corporation, and ExxonMobil Corporation, producing historical compound annual growth rates cited in analyses by Morningstar, Inc. and S&P Dow Jones Indices. Periods of strong performance correspond with technological revolutions led by Intel Corporation, Microsoft Corporation, and Apple Inc., while downturns align with shocks like the Dot-com bubble collapse and the Great Recession. Academic studies by scholars affiliated with institutions like Harvard University, University of Pennsylvania, and Massachusetts Institute of Technology evaluate risk-adjusted returns relative to factors from the Fama–French framework and Nobel laureates such as Eugene Fama and Robert Shiller contribute to debates on expected returns.

Criticisms and Limitations

Critiques focus on concentration risk as a few megacap firms such as Apple Inc., Microsoft Corporation, Amazon (company), and Alphabet Inc. can dominate index weight, and on representativeness concerns given omissions of small-cap or private firms akin to SpaceX or Stripe. Other limitations noted by commentators at The Economist and scholars at Columbia University involve survivorship bias, sectoral skew toward technology and finance exemplified by Goldman Sachs Group, Inc. and Visa Inc., and potential conflicts of interest when index providers like S&P Global set inclusion criteria. Debates also address passive investing impacts on price discovery as discussed in forums featuring participants from Harvard Business School, London Business School, and regulatory bodies including the Financial Conduct Authority.

Category:Stock market indices