Summer Index Rebalances: How They Work and Why They Matter

While summer activities take center stage, the financial markets are busy with key index rebalances. Between late May and the end of June, major index providers like S&P Dow Jones, MSCI, and FTSE Russell undertake significant rebalancing efforts. These events can potentially help benchmarks maintain exposure to companies within their targeted asset class or markets, but the rebalancing can also impact investment portfolios. Let’s take a closer look.

For many investors, an allocation to an index investment is an important part of their portfolio, such as an S&P 500 ETF, a Russell 2000 mutual fund, or an MSCI Emerging Markets Index fund. While index investing gives participants exposure to specific asset classes, many may not realize how often indexes change because it looks like a single, unchanging holding on a quarterly statement. Regular rebalances of these indexes are crucial for maintaining accurate exposures within benchmarks. S&P and MSCI rebalance quarterly, while the Russell index family makes most changes annually during the Russell Reconstitution in late June, involving stocks moving in and out of the various Russell indexes.

In this year’s Russell Reconstitution, 38 stocks moved into the Russell 1000 Large-Cap Index, with 27 migrating from the Russell 2000 Small-Cap Index. Conversely, 32 stocks left the Russell 1000, mostly moving into the Russell 2000. Additionally, the Russell 2000 Small-Cap Index saw 206 stocks added and 142 stocks deleted. These movements are designed to help FTSE Russell adjust their benchmarks to accurately reflect targeted exposures. Without regular rebalancing, indexes like the Russell 2000 could end up holding mid-cap, large-cap, and some micro-cap stocks and miss new small-cap stocks.

As benchmark providers update their indexes, asset managers responsible for managing ETFs, mutual funds, and other index funds must also adjust their holdings. Portfolio managers use their expertise to align funds with benchmark exposures, a process that can involve significant trading. It’s estimated that asset managers executed trades valued at over $140 billion for the Russell Reconstitution. As a significant index investor ourselves, Northern Trust Asset Management manages these events and all upcoming index rebalancing events with our usual care and diligence.