Block Deals and Bulk Deals: How to Track Big Institutional Trades and What They Signal

Last Reviewed and Updated: 17 Aug 2026

Twice a day, in two windows lasting fifteen minutes each, some of the largest single trades on the Indian stock market happen entirely outside the order book everyone else is watching. These are block deals.

A related but genuinely different mechanism, the bulk deal, happens in plain sight, inside the market's normal trading volume, and only becomes visible as a labelled event after the exchange discloses it once markets close. Both leave a public, free, same day paper trail. Both get chased by investors looking for a signal in what a large institution just did. Neither is quite as simple to read as big investor bought, therefore good.

Understanding the mechanics behind these reports, why a trade went through a special window instead of the regular market, why the reported price sits exactly where it does, and who is actually named on each side, explains far more than the headline number ever will on its own. It also explains why chasing a stock the day after a large purchase shows up in these reports is a much less reliable strategy than it first appears.

A bulk deal is not a separate trading mechanism at all. It happens through the regular market, the same continuous order matching every retail trade goes through, and it earns the label only after the fact, when a single client's total buying or selling in one stock on one day crosses 0.5% of that company's total listed shares.

Because it executes in the open market, a bulk deal is already reflected in that day's price and volume in real time, well before anyone can label it as such. NSE and BSE publish bulk deal reports after market hours each trading day, listing the client code, whether the trade was a purchase or sale, the quantity, the price and the security involved.

A block deal is structurally different. It is a single, privately negotiated trade between two parties, executed through a dedicated block deal window rather than the regular order book, specifically so that a very large transaction does not move the market price the way placing the same order in the open market might.

Under the current framework, a morning window runs from 8:45 to 9:00 am, priced against the previous day's closing price, and an afternoon window runs from 2:05 to 2:20 pm, priced against the volume weighted average price of trades between 1:45 and 2:00 pm, calculated and published just before the window opens.

Orders must sit within a defined band of that reference price, the two counterparties' quantity and price must match exactly, and every executed block deal must result in actual delivery of shares, with no squaring off or reversal permitted within the day.

Feature	Bulk Deal	Block Deal
Where it executes	Regular market, continuous trading hours	Two dedicated windows, 8:45 to 9:00 am and 2:05 to 2:20 pm
Threshold	Single client crosses 0.5% of the company's listed shares in a day	Minimum order size of Rs 25 crore since December 7, 2025
Visibility	Reflected in real time market price and volume as it happens	Not visible until the window closes and the exchange discloses it
Reversal	Ordinary trading rules apply	Mandatory delivery; cannot be squared off or reversed intraday
Disclosure	Published by exchanges after market hours the same day	Published immediately after the relevant window closes

SEBI notified a comprehensive revision of the block deal framework on October 8, 2025, which took effect December 7, 2025. The minimum order size rose from Rs 10 crore to Rs 25 crore, and the permitted price band widened from plus or minus 1% to plus or minus 3% of the reference price, intended to reduce execution failures under the old, narrower band.

The revision also formalised disclosure of client identities and extended the framework to cover trades settled under the optional T+0 settlement cycle. SEBI's own analysis of block deal activity on NSE through FY25 found that 90% of block deals already exceeded Rs 14 crore, 75% exceeded Rs 26 crore, and half exceeded Rs 84 crore, suggesting the new Rs 25 crore floor mostly formalises where genuine institutional activity already concentrated rather than dramatically narrowing who can use the window.

FY25 NSE Block Deal Size	Share of Deals At or Above This Size
Rs 14 crore	90%
Rs 26 crore	75%
Rs 50 crore	60%
Rs 84 crore	50%

Both NSE and BSE publish bulk and block deal data directly on their own websites, updated after market hours each trading day, and this remains genuinely free, public information rather than anything requiring a paid subscription.

Most brokerage platforms and financial data portals mirror this same data in a more searchable, filterable dashboard, often adding client name lookups or historical trends for a specific stock, which can save the effort of parsing the exchanges' raw daily files directly.

It is worth sitting with one structural fact about block deals specifically: because the mechanism requires an exactly matching quantity and price on both sides, every single block deal is, by construction, one investor's exit funding another investor's entry in the same instant.

A block deal report does not tell you the market as a whole grew more bullish or bearish that day. It tells you that one specific counterparty wanted out at a specific price and another specific counterparty wanted in at that same price, nothing more. Reading direction into a single block deal, without knowing why either side actually made that decision, is reading more into the data than the mechanism itself can support.

A block deal report never tells you the market got more bullish or bearish that day. It tells you exactly one investor's exit was exactly another investor's entry, at a price both sides agreed to in advance.

None of this means bulk and block deal data is useless, only that it needs context. Repeated bulk or block purchases in the same stock by the same or similar categories of buyer over several days or weeks is a meaningfully stronger signal than any single reported trade, since persistence suggests a considered position being built deliberately rather than a one off transaction.

A large purchase alongside other corroborating information, an improving business outlook, a new institutional mandate being deployed, or a stake being built ahead of a broader corporate action, carries more weight than the trade in isolation. Large, sustained selling by a promoter, particularly outside a known, pre disclosed reason such as a planned stake sale, is generally worth understanding before assuming it is simply routine portfolio management.

A great deal of bulk and block deal activity reflects reasons that have little to do with a fresh view on the company itself. Mutual funds facing redemption pressure may need to sell regardless of their conviction in a specific holding. Private equity or venture investors routinely exit through block deals once a listing lock in period expires, a scheduled, planned event tied to that fund's own return of capital timeline rather than a judgement on the company's future.

Institutions occasionally shift positions between related entities or restructure a fund of funds internally, producing a large reported trade that reflects internal bookkeeping more than a market view. Assuming every large reported buy or sell reflects a fresh, informed opinion about the company is the most common way this data gets misread.

A few practical habits are worth carrying into how this data actually gets used:

• Treat a single, isolated bulk or block deal as one data point about a relationship between specific counterparties, not a verdict from the market as a whole.

• Look for persistence across several days or weeks in the same stock and direction before treating institutional activity as a meaningful signal worth acting on.

• Check whether a seller's activity has an obvious, disclosed explanation, such as a lock in expiry or a previously announced stake sale, before assuming distress or lost conviction.

• Remember that by the time a report is public, the trade is already complete and the stock's price may already reflect it, which limits how much of an edge simply reacting to yesterday's report can realistically provide.

• Use the free NSE and BSE disclosures directly, or a platform that mirrors them, rather than relying solely on secondhand summaries that may omit the client identity or category context that makes a specific trade easier to interpret.

Disclaimer

The content on this website is for informational and educational purposes only and should not be construed as investment advice, a recommendation, or a solicitation to buy or sell any security, mutual fund, or financial instrument. Equity Research India is not a SEBI-registered investment advisor or research analyst, and nothing on this site constitutes personalized financial advice.

Mutual fund investments are subject to market risks. Please read all scheme-related documents carefully before investing. Past performance is not indicative of future returns. NAV, returns, rankings, and other data may change and may not reflect the most current information at the time of reading.

Readers should conduct their own due diligence and consult a SEBI-registered financial advisor before making any investment decisions. Equity Research India and its authors accept no liability for any loss or damage arising from the use of this content.

Rules, thresholds and figures cited reflect SEBI and exchange circulars as publicly available at the time of writing and are subject to change. Past institutional trading activity is not indicative of future stock performance. Readers should consult a SEBI registered investment adviser before making investment decisions.