Index Insights: Stories from the September 2023 S&P rebalance

Samara Cohen Sep 13, 2023 Equity

In this edition of Index Insights, we explore what we expect to happen during the September 2023 S&P Dow Jones Indices (S&P DJI) Quarterly Index Rebalance including:

  • Elevated turnover in small and mid cap indices. Due to a change in the S&P DJI methodology, turnover levels are expected to be elevated for the S&P MidCap 400 Index and the S&P SmallCap 600 Index compared to the September 2022 rebalance.1
  • Notable additions to the S&P 500 Index. On the back of changes to the S&P DJI methodology, which now allows for companies with multiple share classes of stock to be included in the S&P Composite 1500 Indices, Blackstone and Airbnb are expected to be added into the S&P 500® Index.2

Index providers, like MSCI or FTSE Russell, are responsible for constructing and monitoring a wide variety of indexes.

During periodic reviews (or rebalances), index providers may make changes to their indexes. For example, a provider will remove securities that no longer meet the criteria for index inclusion as outlined in its methodology.

Unlike individual securities, indexes aren’t directly investable. Instead, investors use index funds, including index ETFs, which are designed to track the performance of designated indexes, less fees. Given the rise in usage of index funds, large amounts of assets now seek to track these indexes.3

That’s why it’s important for investors to monitor index rebalances. Updates to index holdings, like additions to, deletions from and weight changes within an index, may have a corresponding impact on iShares ETFs.

For more information on these changes and their potential impact on the funds listed below, see the full report.

Samara Cohen

Samara Cohen

Managing Director, Chief Investment Officer of ETF and Index Investments

Samantha Merwin, CFA

Head of EII Markets Advocacy


Alec Woodworth, CFA

EII Markets Advocacy


Brian Goodwine, CFA

EII Index Research