Market Microstructure

Market microstructure is the study of how markets actually work at the granular level — how orders are matched, how prices are formed, and how different participants interact. Understanding microstructure gives you an edge in execution, especially for larger positions.

The Order Book is a real-time list of buy orders (bids) and sell orders (asks) at every price level. The best bid and ask form the "spread." Market orders execute immediately at the best available price. Limit orders sit in the book until filled or cancelled. Order flow imbalance — more buyers than sellers — predicts short-term price direction.

Tick Size and Lot Size matter for liquidity. NSE's minimum tick size for equities is Rs 0.05. For futures, it varies by contract. Smaller tick size means tighter spreads and better liquidity for small orders but creates more noise in the price series.

Market Impact is the price movement caused by your own order. A market buy order for 10,000 shares of a stock with thin liquidity will push the price up as it consumes all available sell orders at each level. Institutional investors use algorithms (VWAP, TWAP, POV) to slice large orders and minimize market impact.

High-Frequency Trading (HFT): Firms using ultra-low-latency systems to trade thousands of times per second. They provide liquidity (market making) but also engage in strategies like latency arbitrage and momentum ignition. SEBI has co-location regulations that limit HFT firms to specific server slots in the exchange data center. For retail traders, HFT is a background factor — not a direct competition.

Price Levels and Institutional Activity: Large round numbers (22,000, 23,000 on Nifty) act as psychological support/resistance because many limit orders cluster there. Options Max Pain — the price at which maximum options expire worthless — has some gravitational pull near expiry as market makers delta-hedge. Not a reliable trading signal alone but useful context.