Market Capitalisation Classification
Market capitalisation classification refers to SEBI's formal definition of large-cap, mid-cap, and small-cap companies based on their full market capitalisation rank among all NSE and BSE-listed stocks, with the classification updated semi-annually and used to govern mutual fund categorisation rules.
Prior to October 2017, the definitions of 'large-cap', 'mid-cap', and 'small-cap' were inconsistent across asset management companies, with each AMC using its own threshold. A mutual fund labelled 'large-cap' by one AMC might hold stocks that another AMC classified as mid-cap. This made it difficult for investors to compare funds or to know what they actually owned. SEBI's landmark circular on scheme categorisation of mutual funds, issued in October 2017, resolved this by mandating uniform, regulator-defined classifications.
Under SEBI's definition, companies are ranked by full market capitalisation (not free-float adjusted) using a combined list of companies listed on NSE and BSE. The top 100 companies by this ranking constitute the large-cap universe. Companies ranked 101 to 250 are mid-cap. All companies ranked 251 and below are small-cap. The 'micro-cap' category is not formally defined by SEBI in these regulations but is colloquially used for the lowest-ranked portion of the small-cap universe.
AMFI (Association of Mutual Funds in India) publishes and updates this classification list every six months—in January and July of each year. The list is based on the average market capitalisation over the preceding six months, reducing the impact of short-term price volatility on classification decisions. A stock oscillating near the boundary between large-cap and mid-cap will not flip classification every month—the six-month average provides stability.
Mutual fund schemes labelled as 'Large Cap Fund', 'Mid Cap Fund', or 'Small Cap Fund' under SEBI's categorisation norms are required to maintain a minimum allocation to their respective defined universe—for example, large-cap funds must invest at least 80% in large-cap stocks as defined by AMFI. This means AMC fund managers must periodically review their portfolios against the latest AMFI classification list and rebalance if a previously large-cap stock falls into the mid-cap universe or vice versa.
For investors, this classification system provides meaningful consistency. Comparing two 'large-cap funds' is now a more apples-to-apples exercise than it was before 2017, since both are operating within the same regulatory universe of the top 100 stocks.