On 18 March 2026, Urban Company's stock jumped as much as 16% in a single session, past Rs 127, after SBI Mutual Fund used a mix of bulk and block trades to buy an additional stake worth around Rs 632 crore. Two mechanisms did the heavy lifting that day, and most investors use the terms bulk deal and block deal interchangeably without realising they follow completely different rules. They are not the same thing, and the difference tells you a lot about how conviction actually enters a stock.
Both describe a single large trade in one stock, big enough that the exchange is required to make it public. Where they diverge is how, and where, that trade actually happens.
Bulk deals happen in plain sight
A bulk deal is simply a very large trade, or several trades by the same buyer or seller on the same day, executed in the ordinary trading window like any other order. The trigger is quantity: if the shares bought or sold add up to 0.5% or more of a company's total listed shares, it counts as a bulk deal, regardless of the rupee value. Because it goes through the live order book, a large bulk buy can eat through the available sellers at each price level and genuinely move the stock, which is roughly what happened to Urban Company that day, as post-IPO lock-in shares hit the market and SBI Mutual Fund absorbed the supply.
Nobody has to personally announce a bulk deal. The exchange itself flags any trade crossing the 0.5% mark from its own data and publishes the buyer, seller, quantity, and price on its website the same evening, after the market closes. You do not need inside access to see it, just a visit to the NSE or BSE bulk deals page.
Block deals happen off to the side
A block deal is prearranged. Buyer and seller agree on a price beforehand and route the trade through a special window set aside for exactly this purpose, away from the regular order book. SEBI rewrote the rules for this window in October 2025, and they took effect on 7 December 2025.
Why the venue changes what you should read into it
The HDFC Bank block deal on 9 January 2026, roughly 1.7 crore shares changing hands for about Rs 1,676 crore, barely dented the stock's live price that day, because the trade was settled privately within its band before it ever touched the open order book. Compare that to Urban Company, where SBI Mutual Fund's buying, some of it routed as a straightforward bulk trade, ran straight into the live market and forced the price up as sellers thinned out. A block deal tells you size and conviction. A bulk deal on the open market can tell you size, conviction, and the price the market was actually willing to pay for that size, all in the same data point.
That distinction matters more with promoters than with mutual funds. When a promoter offloads a chunk of their holding through a bulk deal rather than a slow trickle of small sales, it shows up instantly and publicly, which is one reason bulk deal data gets watched almost as closely as FII and DII flows. A single large sale is not automatically a red flag, since promoters raise money for all kinds of reasons. A pattern of repeated bulk selling alongside a falling promoter stake is worth far more attention than either fact alone.
None of this replaces checking who bought, who sold, and why. A large SBI Mutual Fund purchase and a large FII exit both show up as "big deals," but they say very different things about where conviction is heading. The trade type just tells you where to look for the rest of the story, whether that is a stock's delivery percentage confirming the shares actually changed hands for good, or a company's next shareholding filing telling you if the seller was a promoter or a passing fund.