What It Means
Nifty 50 is the benchmark index tracking the 50 largest and most liquid companies listed on the NSE, weighted by free-float market capitalization. It's the number most Indian traders mean when they say "the market is up" or "the market is down."
How It Works
Because Nifty 50 is free-float weighted, a company's influence on the index depends on its market value and how many of its shares are actually available for public trading, not just its total size — so a couple of large-weight stocks can move the whole index meaningfully even if most other constituents are flat. NSE reviews and reconstitutes the index periodically, replacing underperforming or shrinking companies with ones that have grown into the top ranks (often promoted up from the Nifty Next 50). Nifty 50 also underlies India's most heavily traded index derivatives — futures and weekly options — and most index funds and ETFs tracking "the Indian market" are built to mirror it.