index rebalancing
The periodic adjustment of an index's components when stocks are added or removed, causing index funds to buy newly added stocks and sell removed ones.
Example
“When Tesla was added to the S&P 500, index rebalancing required funds tracking the index to collectively buy $80 billion in Tesla shares.”
Memory Tip
INDEX REBALANCING = index funds MUST buy/sell when the index changes composition. Predictable price impact.
Why It Matters
Index rebalancing affects the costs and performance of index funds and ETFs that you might own in your investment portfolio. Understanding this process helps you appreciate why even passive index investing involves some trading activity and associated costs that can impact your long-term returns.
Common Misconception
Many people believe that index funds never trade or that they are completely passive investments with zero activity. In reality, index funds must regularly buy and sell stocks whenever the underlying index changes its composition, which creates transaction costs and potential tax consequences.
In Practice
When Tesla was added to the S&P 500 in December 2020, all S&P 500 index funds had to simultaneously purchase Tesla shares to match the new index composition. This massive coordinated buying drove Tesla stock prices up temporarily, and the index funds incurred trading costs and potential capital gains taxes that were passed along to their investors.
Etymology
INDEX (market benchmark) REBALANCING (adjusting components). REBALANCING the components of an INDEX.
Common Misspellings
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Related Terms
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See Also
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