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Knowing the potential influences on indices is crucial for a trader who specializes in trading indices. It could be financial factors, geopolitical events, government policies, or index rebalancing - that we must examine.

Learn the idea of index rebalancing - its purpose, methodology, and famous index rebalancing events that influenced financial markets. 


What is index rebalancing? 


Hand adjusting blocks with percentage symbols.


Index rebalancing is a systematic process wherein an index is periodically adjusted to maintain its integrity and accurately reflect the underlying market it seeks to represent. The index can represent various financial markets, such as stock markets, bond markets, or commodity markets. 

Index rebalancing is crucial for investors and traders, who often use indices as benchmarks. It helps them manage risk, stay aligned with current market conditions, and make informed financial decisions.

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Purpose of index rebalancing

Here are a few key reasons why index rebalancing is significant to traders:

  • Reflecting market changes: Markets are dynamic, and the values and behaviors of assets within a particular index can change over time. Index rebalancing ensures that the index accurately mirrors the current state of the market or sector it represents. This, in turn, helps investors make informed decisions and evaluate their portfolios effectively.
  • Preserving index integrity: Without periodic rebalancing, an index can become skewed, leading to a distorted market representation. It is crucial to keep track of the index components and their weights to ensure that the index accurately reflects the market it represents.
  • Adhering to objectives: Many investors use index-based products, such as exchange-traded funds (ETFs) or index mutual funds, as a means to achieve specific financial goals. These objectives include diversification, exposure to particular sectors, or risk management. Proper index rebalancing is essential for these products to continue meeting these objectives.


How does index rebalancing work

1. Stock selection and removal

Index rebalancing begins with a comprehensive evaluation of the components of the index. This stage involves the identification of stocks that no longer meet the index's criteria for inclusion. The removal of these stocks is essential for maintaining the index's representativeness and relevancy. New candidates for inclusion may also be identified during this stage, aligning with the index's objectives.

The index's criteria for removal and inclusion are the following: 

  • Market capitalization:  Indices often include stocks with a minimum market capitalization threshold to ensure that the companies included are of a certain size and significance in the market. For example, a large-cap index might consist of only stocks with a market capitalization above a specific dollar amount.
  • Liquidity: Stocks with higher trading volumes are typically preferred, as they are easier to buy and sell without significantly affecting the market price. Liquidity ensures that investors can replicate the index without undue trading costs.
  • Sector representation: Many indices aim to represent specific sectors or industries. Criteria for sector representation involve selecting companies primarily related to an industry, such as technology, finance, etc. This ensures that the index accurately tracks the performance of that sector.
  • Geographic location: Global indices may require criteria related to the geographic location of companies. For instance, an index tracking US stocks will only include companies that are headquartered or primarily operate within the United States.
  • Trading history: Stocks included in an index should have a history of trading on a stock exchange for a certain period. This criterion helps to filter out newly listed or highly speculative stocks.
  • Governance and regulatory compliance: Criteria related to corporate governance and regulatory compliance, such as adherence to accounting and reporting standards, may be essential for specific indices.
  • Committee decisions: In some cases, an index may have a committee of experts who use their discretion to determine stock inclusion and exclusion based on their knowledge of the market and the index's objectives.

2. Implementation and timing

Once the changes in stock selection are decided, they need to be implemented in a timely and efficient manner. Index providers and fund managers work together to execute these changes in a way that minimizes market disruptions. It involves trading stocks, adjusting portfolio holdings, and communicating these changes to market participants. 

The timing of these changes can have significant implications for investors and traders, as they can impact the performance of index-tracking funds and strategies.


Frequency of rebalancing 

When rebalancing an index, the frequency is determined by the methodology of the index provider and the market conditions it represents. Typically, indices are rebalanced at regular intervals, such as every quarter, semi-annually, or annually. 

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However, some indices may require more frequent rebalancing to keep up with rapidly changing markets. In contrast, other indices, such as long-term or strategic indices, may need to be rebalanced less often.

Indices that are not rebalanced often are referred to as "static" or "fixed-weight" indices. These indices do not adjust their components or weightings based on market conditions or the performance of the underlying assets. As a result, they can become less representative of the current state of the market over time. Here are some examples:

  1. Dow Jones Industrial Average (DJIA): The DJIA is one of the most famous examples of a static index. It consists of 30 large, well-established US companies. Unlike many other indices that rebalance periodically, the DJIA components and weightings are not adjusted frequently. Changes in the index composition are rare and typically occur when there are significant corporate events, such as mergers or financial distress. As a result, the DJIA may not accurately reflect the broader US financial market.
  2. FTSE 100: This is a widely followed British stock market index. It comprises the 100 largest companies listed on the London Stock Exchange. Changes in its composition typically happen every quarter, and they are often based on the ranking of companies by market capitalization.
  3. S&P 500 Equal Weight Index: While the S&P 500 is a dynamic index that rebalances more frequently, there are variations like the S&P 500 Equal Weight Index, which doesn't rebalance as frequently. The S&P 500 Equal Weight Index assigns an equal weight to each of its 500 components, and it only rebalances back to equal weight on a quarterly basis. Companies that have performed exceptionally well can make up a larger portion of the index over time.

Check out this article: How to Trade Indices

Role of index providers and committees

Index providers play a central role in the index rebalancing process. They are responsible for defining the rules and criteria that govern the composition and weighting of the index. 

These rules are developed with the input of committees and experts in the field. Index providers also oversee the selection and removal of stocks, ensuring that the index accurately represents its intended market or asset class.


Business meeting with gGroup of professionals


Index committees, often comprised of industry experts, analysts, and market professionals, provide valuable input and guidance to index providers. They help in setting the rules and criteria for index rebalancing, taking into account the specific goals and objectives of the index. 

Committees may meet periodically to review the performance of the index, and the effectiveness of the rules, and make necessary adjustments in response to changing market conditions.


Well-known index rebalancing events

Here are several unexpected rebalancing events that had a profound impact on the financial markets:

Tesla's Inclusion in the S&P 500 (2020)

In December 2020, Tesla, Inc. was added to the S&P 500 Index. This event was notable because Tesla had become one of the most valuable companies in the world by market capitalization, and its inclusion in the S&P 500 required significant rebalancing. 

Index funds and other investors tracking the S&P 500 had to adjust their holdings to accommodate Tesla's substantial weighting in the index.

Apple's 2014 stock split and DJIA rebalancing

In 2014, Apple executed a 7-for-1 stock split. This event immediately initiated a rebalancing of the Dow Jones Industrial Average (DJIA) because the DJIA is a price-weighted index. Following the split, Apple's stock price was significantly lower, and Visa was added to the DJIA to maintain the index's representation of the technology sector.

Facebook, Alphabet’s Addition to the S&P 500's communication services sector (2018)

In September 2018, S&P Dow Jones Indices reclassified companies within the S&P 500. Facebook, Alphabet (Google's parent company), and other companies were moved from the Information Technology sector to the new Communication Services sector. This change was significant as it affected the sector composition of the S&P 500 and various sector-specific ETFs.

NVIDIA's inclusion in the NASDAQ-100 index (2017)

In 2017, NVIDIA Corporation, a leading graphics processing unit (GPU) manufacturer, was added to the NASDAQ-100 Index. This inclusion highlighted the company's rapid growth and importance in the technology sector, resulting in the need for index-tracking funds and investors to rebalance their portfolios.

Mega-Tech stock weight adjustments in the S&P 500 (2020)

Throughout 2020, the market capitalization of major tech companies like Apple, Amazon, Microsoft, and Google (Alphabet) continued to surge, leading to substantial changes in their weightings within the S&P 500. 

These adjustments significantly impacted index-tracking funds and investors as they had to adapt to the changing compositions of these mega-cap stocks within the index.


Learn more about index rebalancing at

Index rebalancing is necessary to accurately reflect the underlying markets they represent. This systematic process involves adjusting an index periodically to preserve its integrity. It helps traders and investors manage risk, stay aligned with current market conditions, and make informed financial decisions. 

Index rebalancing involves evaluating index components, including stock selection and removal, based on market capitalization, liquidity, sector representation, geographic location, trading history, governance and regulatory compliance, and committee decisions. 

The process is also perfectly timed by index providers and fund managers to execute these changes in a way that minimizes market disruptions. 

Check out our list of popular indices you can trade through a contract for differences (CFDs). In this type of trading, you will be speculating the price of your chosen indices without having an actual asset. 

In case you want to expand your knowledge of financial trading, here are some basics of trading you need to know to help get you started on your trading journey.

Become a member of, access a cutting-edge trading platform, and start trading in CFD indices today.  

When considering "CFD indices" for trading and price predictions, remember that trading CFDs involves a significant degree of risk and could result in capital loss. Past performance is not indicative of any future results. This information is provided for informative purposes only and should not be construed to be investment advice."

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