A new study has made explosive claims about the world’s largest stock benchmark: Major U.S. corporations that purchase ratings from S&P Global Inc. have a higher chance of entering the S&P 500 Index -- even when they don’t meet all criteria for inclusion.
The non-peer reviewed paper from academics at the Australian National University and Columbia University, published by the National Bureau of Economic Research, suggests companies are seeking to curry favor with the index provider by buying additional services.
The study titled “Is Stock Index Membership For Sale?” threatens to fuel controversy over the far-reaching impact of the gauge tracked by more than $13 trillion in capital. With every adjustment moving billions of dollars around the world, inclusion is a game-changer for boardrooms across America.
“The S&P has likely exercised a nontrivial amount of discretion in deciding which firms to add to the index,” authors Kun Li and Xin Liu at ANU and Shang-Jin Wei at Columbia wrote in the study. “Data patterns suggest that the discretion is often exercised in a way that encourages firms to buy fee-based services from the S&P.”
In a statement, S&P Global described the working paper as flawed.
“S&P Dow Jones Indices and S&P Global Ratings are separate businesses with policies and procedures to ensure they are operated independently of one another,” it said. “Our Index Governance segregates analytical and commercial activities to protect the integrity of our indices. For 64 years, the S&P 500 has provided an independent, transparent and objective benchmark of the U.S. large cap equity market.”
Deviations
At first blush, there’s an easy explanation for the study’s results: A growing company solicits a credit rating in order to finance expansion efforts -- a move that can help the firm graduate into the index on its own merit.
To obtain a rating, corporate borrowers pay an agency such as S&P Global Ratings to assess their creditworthiness.
The three authors found that when an opening is expected on the S&P 500, potential entrants tend to acquire more ratings from S&P -- but not those from rival Moody’s Investors Service, which isn’t a major index provider. That’s especially the case when recent additions enjoy big price jumps, making inclusion ever-more attractive.
The index provider uses a high degree of discretion to decide which firms get in, the researchers said. They found official S&P 500 criteria explained only about 62% of membership of the gauge in the period studied and just 3% of additions. Those percentages are far lower than for the London Stock Exchange’s Russell 1000 Index, they said.