Sensex: BSE 30 Index Explained
Sensex (S&P BSE Sensex) is the benchmark equity index of the Bombay Stock Exchange (BSE), comprising 30 of the largest, most actively traded stocks listed on BSE, weighted by free-float market capitalisation.
Methodology: free-float market capitalisation weighted, with base value 100 set on April 1, 1979 — making Sensex the oldest index in India. Reconstitution semi-annually by S&P Dow Jones Indices and BSE. Selection criteria include listing history (minimum 1 year), trading frequency (95%+ of trading days), market cap among the top 100 BSE companies, sector representation, and listed for at least one year.
Composition (indicative, varies by reconstitution): typically dominated by HDFC Bank, Reliance Industries, ICICI Bank, Infosys, TCS, ITC, L&T, HUL, Bharti Airtel, Bajaj Finance, SBI, Kotak Mahindra Bank, Axis Bank, M&M, Maruti Suzuki, Asian Paints, Sun Pharma, Titan, Tech Mahindra, NTPC. Sectoral weights typically: financials 35-40%, IT 13-15%, energy 10-12%, FMCG 8-10%, auto 5-7%, others.
ETFs that track Sensex: SBI BSE Sensex ETF (SBISENSEX), Nippon India ETF Sensex, HDFC Sensex ETF, ICICI Prudential BSE Sensex ETF. Lower expense ratios (0.05-0.10%) compared to active mutual funds. BSE Sensex Index Fund variants also exist as direct mutual fund schemes. Comparison with Nifty 50: Sensex has 30 stocks (smaller, more concentrated), Nifty 50 has 50 stocks (broader). Both are highly correlated (correlation > 0.99 historically).
Richify Tip
Sensex points are not directly comparable to other indices like S&P 500 because base values and methodologies differ. What matters is the percentage change. Historic milestones: 1,000 (1990), 10,000 (2006), 50,000 (2021), 75,000 (2024). Annualised return since 1979 has been ~14-15% in INR terms (price returns; total returns higher with dividends).
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