The competitive effects of S&P 500 Index revisions
研究发现，被纳入标普500指数的公司相比同行业竞争对手获得竞争优势，表现为股价上涨、融资约束降低和资本投资增加，而竞争对手股价下跌；但剔除指数的影响不对称。
Abstract Firms added to the S&P 500 Index gain a competitive advantage over their non‐S&P 500 industry competitors. They experience positive stock valuation effects at the expense of competitors. The inclusion is associated with both reductions in financial constraints and the cost of equity and increases in capital investment for the newly added firms. When the increase in capital investment is greater, they gain more market share and enjoy better valuation effects. Rivals’ share price responses are negatively related to the announcement effect of the newly added firm. Deletions from the index, however, do not have symmetric effects.