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Market Intelligence › Basic Terminologies
What beta means, how it is calculated, and its limits
Published by The Retail Trader · JUL 23, 2026 · Risk Management
Beta is a number that shows how much your stock or portfolio typically moves when the index moves one percent. It measures sensitivity, not direction.
A beta near one means behaviour like the index. More than one means faster than the index, in both directions. Less than one means slower than the index.
A portfolio's beta is the weighted average of the betas of its holdings. So a high beta stock in a small quantity does not move the whole portfolio that much.
It is wrong to take beta as the whole truth:
• It is derived from historical data — there is no guarantee it will stay the same in the future.
• It only measures the relationship with the index, not the stock's own risk.
• During a crash, most betas run towards one.
• Taking a different period changes the beta number quite a lot.
Knowing your portfolio's beta gives you a simple stress test — if the index fell ten percent, roughly how much would your portfolio fall. Only by looking at that number do you find out whether your portfolio is as conservative as you thought.
This article is for education only — it is not a buy or sell recommendation, makes no claim of guaranteed returns, and is not advisory. Rules, rates and mechanics are changed from time to time by the exchanges, SEBI and RBI, so verify every number yourself with your broker or an official source.