India's passive investing boom has reached unprecedented scale, with assets under management in passive schemes standing at ₹14.84 trillion as of February 2026, representing a ninefold increase from ₹1.63 trillion in 2020, according to NSE Indices' Nifty Passive Insight report released in March. The passive universe now spans 677 schemes and 54 million folios, with 67% of AUM in equity, and more than half of that benchmarked to the Nifty 50. This shift towards passive investing represents one of the defining trends of this decade, driven by the foundation that Nobel laureate William Sharpe established in his 1991 paper arguing that after costs, the average actively managed dollar must underperform its passive counterpart.
NSE's April Market Pulse report reveals that India's overall market concentration has decreased significantly, with the Herfindahl-Hirschman Index (HHI) falling from 202 in 1995 to 81 in 2025, reflecting steady dispersion of market capitalisation across a wider set of companies. However, the concentration within index funds remains substantial. The Nifty 50 averages an HHI of 457 across annual factsheets from March 2017 to March 2026, while the Nifty Next 50 shows a lower HHI of 244. When measured by effective number of stocks, the Nifty 50 averages 22 stocks while the Nifty Next 50 comes in at 41 stocks, indicating that despite identical stock counts, weight distributions create very different concentration levels.
Financial services have emerged as a dominant sector, accounting for 25% of India's total listed market capitalisation as of April 2026, up from 10% in 1995, according to the Market Pulse report. Within the Nifty 50, financial services make up approximately 35% of index weight as of March 2026. Analysis of NSE index factsheets from 2017 to 2026 shows that sector-level HHI has averaged above 1,100 over the past decade, with financial services, IT and refineries together accounting for 52-66% of the index each year. This concentration extends beyond individual stocks to sector-level weightings, creating significant exposure to specific industry segments.
SEBI regulations include a clear safeguard that no diversified equity fund may invest more than 10% of its net asset value (NAV) in a single stock, though passive funds are exempt because they replicate indices. When HDFC Bank's free-float market cap reaches 13% of the Nifty 50, every fund tracking the index holds it at that weight with no discretion. While this framework is deliberate and appropriate, it means concentration limits governing active funds do not apply to passive ones. The cost advantage of the Nifty 50 at expense ratios of 0.10-0.20% compared to 1.00-1.75% typically charged by active large-cap funds remains a key advantage.
Academic research on passive investing has begun examining potential long-term effects as more capital flows into market-cap-weighted indices, with the largest stocks attracting proportionally greater passive inflows that can expand their market capitalisation and index weight. Some researchers argue this dynamic can amplify skew over time, dampen price discovery and raise correlations among index constituents. The long-term systemic effects of passive investing at scale remain an open question, though the cost advantage, behavioural discipline and long-term performance record of passive investing are well established. For investors building passive portfolios, understanding weight distributions and evolution across segments becomes crucial for achieving intended diversification outcomes.
