Market Index
A plain-English definition of a market index and why indexes are not interchangeable.
Plain-English definition
A market index is a basket that tracks the performance of a defined segment of the market, such as the S&P 500.
Why it matters
Indexes provide market context and benchmarks, but each one represents a different slice of exposure.
Beginner example
The Nasdaq 100 has a different tilt from the S&P 500 even though both are major US equity indexes.
Common misunderstanding
An index is not the whole market. It is one representation of part of the market.
Practice with Alpha Council
Explain what a market index is and why there are several of them.
Not Financial Advice
This learn page is for education and research workflow guidance only. It explains concepts, metrics, and analysis steps used inside Alpha Council. It does not provide personalized investment advice, guaranteed outcomes, or automated trading instructions.