About Stock Market Indices
Major U.S. Indices
- S&P 500 — 500 largest U.S. companies, representing ~80% of total market capitalization. The most widely followed benchmark for large-cap equities.
- NASDAQ 100 — 100 largest non-financial companies on NASDAQ, heavily weighted toward technology and growth stocks.
- Dow Jones — 30 blue-chip companies selected to represent major U.S. industries. The oldest continuously published stock index.
Market Capitalization
- Mega-Cap — Over $200 billion (Apple, Microsoft, Amazon)
- Large-Cap — $10B to $200B (established, stable companies)
- Mid-Cap — $2B to $10B (balance of growth and stability)
- Small-Cap — $300M to $2B (higher growth potential, more volatile)
- Micro-Cap — Under $300M (highest risk and reward potential)