Index rebalancing is a periodic process through which the composition of a stock market index is reviewed and updated to reflect changes in market value, liquidity and eligibility. As companies grow, lose market share, merge or fall below the required criteria, they can be added to or removed from an index.
The recent BSE-Wipro reshuffle in the Nifty 50 offers a clear example of how an index rejig works, what triggers such changes and how investors may be affected.
What is index rebalancing and why does it happen?
A stock market index comprises a selected group of companies designed to represent a particular segment of the market. Stocks are selected based on parameters such as market capitalisation, free-float market capitalisation, liquidity and other eligibility criteria.
As these factors change over time, the composition of an index may also need to be updated. This review process is known as index rebalancing or an index rejig.
Major indices such as the Nifty 50 and Sensex are reviewed twice a year, although the frequency can vary across indices. Some sectoral and thematic indices may undergo annual reviews, while others may also undergo periodic checks or adjustments to stock weights.
BSE replaces Wipro in Nifty 50
The latest Nifty 50 reshuffle provides a recent example of this process. BSE Limited replaced Wipro Limited in the benchmark Nifty 50, with the change becoming effective from 30 September 2026, following the close of trading on 29 September.
According to the NSE Indices review, BSE had a six-month average free-float market capitalisation of around ₹1,40,879 crore, significantly higher than Wipro’s ₹55,930 crore.
Under the index methodology, an eligible stock’s six-month average free-float market capitalisation needs to be at least 1.5 times that of the smallest Nifty 50 constituent for inclusion. BSE met this requirement, resulting in its entry into the index, while Wipro moved to the Nifty Next 50.
What happens to stocks entering or exiting an index?
The impact of an index rejig is not limited to the index itself. It can also influence trading activity in the stocks being added or removed because passive funds such as index funds and exchange-traded funds (ETFs) seek to align their portfolios with the index.
Abhinav Tiwari, Sr. Research Analyst at Bonanza, said the BSE-Wipro change was largely mechanical and driven by factors including free-float market capitalisation and liquidity.
He said BSE’s inclusion could result in forced buying by passive funds, while Wipro’s exclusion could lead to selling by funds tracking the Nifty 50.
However, Tiwari noted that such mechanical buying and selling pressure generally eases once the rebalancing is completed. As a result, some of the price movement seen ahead of the effective date could reverse after the passive flows have been absorbed.
For Wipro, the move to the Nifty Next 50 does not eliminate passive-fund demand altogether, as funds tracking that index may continue to hold the stock, he added.
Does entering an index always mean a stock will rise?
Not necessarily.
Dr V K Vijayakumar, Chief Investment Strategist at Geojit Investments, said stocks entering an index normally attract buying because passive funds need to replicate the new index composition. This can create additional demand and potentially support the stock price.
However, he pointed out that the impact is not guaranteed. If the broader market is weak and investors expect further downside, those who bought the stock in anticipation of index inclusion may choose to exit, offsetting the buying triggered by passive funds.
The same principle applies to stocks removed from an index, Vijayakumar said. While exclusion can result in selling from passive funds tracking the index, broader market sentiment and investor expectations can influence the actual price reaction.
What do the charts say about BSE and Wipro?
While the index change itself is mechanical, the two stocks’ technical setups remain an important consideration.
Chandan Taparia, Head – Derivatives & Technicals, Wealth Management at Motilal Oswal Financial Services, said Wipro has given a range breakdown on the monthly chart, indicating a weak setup. He expects every small bounce to face selling pressure, with ₹145 as a potential downside level and ₹170 acting as a hurdle.
On BSE, Taparia said the stock has formed lower highs and lower lows over the past four months, pointing to a technically weak setup. He identified ₹2,750 and ₹2,500 as downside levels, while ₹3,150–3,200 remains a hurdle on the upside.
What should investors understand from an index rejig?
The BSE-Wipro change highlights that an index rejig is primarily a rules-based exercise rather than a fresh fundamental assessment of a company. A stock can enter or exit an index because its market capitalisation, liquidity, or other eligibility parameters have changed relative to those of other constituents.
For investors, the immediate impact can come from passive fund flows and the resulting buying or selling pressure. However, once those flows are absorbed, the stock’s subsequent performance can continue to depend on its earnings, business outlook, valuations and broader market conditions.
In the BSE-Wipro case, therefore, the index change explains the potential mechanical impact on flows, while analysts’ technical views point to price levels investors may watch after the rejig.
Disclaimer: This story is for educational purposes only. The views and recommendations above are those of individual analysts or broking companies, not Mint. We advise investors to check with certified experts before making any investment decisions.
About The Author
