Market Structure

The plumbing. Most of what feels inexplicable about a day's price action is explained by one of the terms on this page.

Liquidity is the term that explains the most

Liquidity is how much you can trade without moving the price against yourself. It is invisible when you have it and it is the entire story when you don't. Everything else in this group is a measurement of it or a consequence of it.

The bid-ask spread is the cheapest available reading: the gap between the best buy and best sell price is what you pay, immediately, for the privilege of transacting now. On NIFTY at the money it is negligible. On a far out-of-the-money strike in a mid-cap stock it can be several percent of the premium, which quietly makes a strategy unprofitable no matter how good the analysis behind it was.

Market depth, the order book, is the fuller picture — how much size is resting at each price on both sides. It is the difference between a level that will hold and one that only looks like it will. A large order sitting on the bid is real support in a way that a line drawn on a chart is not, with the caveat that a resting order can be cancelled the instant it is tested.

Indian-market specifics

Circuit breakers are the exchange's hard limits: individual stocks have price bands, and index-wide moves of 10%, 15% and 20% halt trading market-wide for defined periods. A stock locked in an upper circuit has no sellers at that price, which means the quoted price is real but the ability to transact at it is not — a distinction that matters enormously if you are holding options on it.

An index like NIFTY 50 is a weighted basket, and free-float market-capitalisation weighting means the largest constituents drive it. NIFTY can rise on a day when most of its constituents fell, if the heavyweights carried it. That is not a paradox; it is arithmetic, and it is why the advance-decline ratio is worth reading alongside the index level. Breadth tells you whether a move is broad or whether it is four stocks.

Sector rotation is money moving between sectors rather than in or out of the market. A flat index with banks up and IT down is not a quiet day — it is an active one that the index number is hiding.

Short selling and the squeeze

Short selling is selling something you don't own, which in the Indian cash market must be squared off the same day unless done through the derivatives segment. Short covering is those positions being bought back.

The reason short covering has its own entry is that it produces rallies that look like buying and are not. Price rises sharply while open interest falls — people are leaving, not arriving. These moves are fast, they are usually the sharpest of any given week, and they end abruptly when the shorts are done, because nothing was actually being accumulated. The change-in-OI reading on the option chain is the cleanest way to tell the two apart in real time.

All 10 terms in Market Structure

Alphabetical, each with a worked example. Every one of these is searchable from the glossary index.

Advance-Decline Ratio

The number of rising stocks versus falling ones — a market breadth gauge. A rally led by only a few stocks (weak breadth) is fragile.

e.g. NIFTY is green but 35 of its 50 stocks are red → weak breadth; the index is being carried by a few heavyweights.

Bid-Ask Spread

The gap between the highest price buyers will pay (bid) and the lowest sellers will accept (ask/offer). A narrow spread signals a liquid, efficient market.

e.g. Bid ₹250.10 / Ask ₹250.15 → a tight ₹0.05 spread (liquid). Bid ₹250 / Ask ₹252 → a ₹2 spread (illiquid).

Bull Market / Bear Market

A bull market is a sustained rise (optimism); a bear market is a sustained fall, conventionally 20%+ off the highs (pessimism).

e.g. NIFTY grinding up for months on strong flows = a bull market; a 20%+ drop from the top = a bear market.

Circuit Breaker

An exchange-imposed price band that halts trading in a stock/index after an extreme move (upper or lower circuit), to curb panic and manipulation.

e.g. A stock with a 10% band closes at ₹100; it can't trade above ₹110 (upper circuit) or below ₹90 (lower circuit) next day.

Index

A basket of stocks tracked as one number to represent a market or sector. NIFTY 50 and SENSEX are India's headline benchmarks.

e.g. NIFTY 50 bundles 50 large companies into one number — when it's 'up 1%', the broad large-cap market rose ~1%.

Liquidity

How easily an asset can be traded without moving its price. High liquidity = tight spreads and deep order books; low liquidity means bigger slippage.

e.g. RELIANCE fills a large order instantly; a thin small-cap jumps ₹5 the moment you buy a modest quantity.

Market Depth (Order Book)

The stack of pending buy and sell orders at each price. Shows where liquidity sits and how much size it would take to move the price.

e.g. The depth shows 50,000 shares bid at ₹250 but only 2,000 offered at ₹251 → thin supply overhead, easy to push up.

Sector Rotation

The flow of money between sectors as the economic cycle turns — e.g. into cyclicals in a recovery, into defensives in a slowdown.

e.g. As rate-cut hopes rise, money rotates out of defensive FMCG into rate-sensitive banks and autos.

Short Covering

Short sellers buying back to close positions, which pushes price up. A rapid, forced version is a short squeeze.

e.g. A heavily-shorted stock pops 8% on good news; panicked shorts buy back to cut losses, fuelling a short squeeze even higher.

Short Selling

Selling a borrowed asset hoping to buy it back cheaper — a bet that the price will fall. Losses are theoretically unlimited if price rises.

e.g. Short a stock at ₹500 and cover at ₹460 → ₹40 profit. But if it rallies to ₹560, you lose ₹60.

Definitions are written for people learning to read a market screen, not as legal or regulatory definitions, and nothing on this page is investment advice — see the disclaimer. Spotted something wrong or unclear? Tell us.