What it means
The mechanics almost always involve an investment bank standing in the middle. The bank either finds buyers first and then matches them to the seller, known as an agency or best efforts deal, or buys the whole block onto its own balance sheet at an agreed price and resells it, known as a bought deal.
The seller pays for that certainty with a discount. Because the buyers are taking on price risk and a chunk of stock they cannot easily resell, the block is priced below the last traded price, commonly by anywhere from 2% to 10% depending on how liquid the shares are.
For company management, a block trade in their own stock is an event to manage rather than to fear. It changes the shareholder register in a single afternoon, often replacing one large holder with a spread of institutions, and it can create a short, sharp dip in the share price that has nothing to do with trading performance.
A common variant is the accelerated bookbuild, where the bank opens the book after the market closes and prices the entire block within a few hours. Regulators generally require the trade to be reported, sometimes with a short delay so that the buyer can manage the risk it has just taken on.
Anyone reading a price chart should treat a sudden volume spike alongside a price gap as a possible block. Lock-up agreements are the other piece of the puzzle.
After a flotation, insiders are usually barred from selling for a set period, and the first block trade after a lock-up expires is often the largest single day of volume the stock has seen. Experienced investors watch expiry dates carefully for exactly that reason.
In practice
Real-world examples
Example 1
A family that founded a listed engineering group sells 3,000,000 shares through an overnight block to fund an inheritance tax bill. The bank builds a book of twelve institutional buyers before the market opens and prices the block at a 4% discount, so the family receives cash within two days.
Example 2
A government disposes of part of its stake in a rescued bank through a series of block trades rather than a public offer. Each block is small enough to be absorbed quietly, and the government publishes the price achieved so taxpayers can see the terms.
Example 3
A hedge fund unwinding a concentrated position asks three banks to bid for the whole block on a risk basis. The winning bank buys the shares outright at a 6% discount and spends the following week distributing them, keeping any upside and bearing any loss.
Think of it
Selling a million shares on the open market is like trying to empty a swimming pool with a teaspoon, causing a chaotic splash. A block trade is like opening a large drainpipe to move the water smoothly.
Formula
Calculation
Block trade gross proceeds = shares sold x offer price. Discount = (reference price - offer price) / reference price.
A private equity firm sells 4,000,000 shares in a listed logistics company. The shares closed at $30.00, and the bank prices the block at $28.50. The discount is ($30.00 - $28.50) / $30.00 = 5.0%. The firm receives 4,000,000 x $28.50 = $114,000,000 in gross proceeds, which is $6,000,000 less than the closing market value of 4,000,000 x $30.00 = $120,000,000. After an underwriting fee of 1.5%, or $114,000,000 x 0.015 = $1,710,000, net proceeds are $114,000,000 - $1,710,000 = $112,290,000.Case study
Seen in the real world
The following is an illustrative and entirely fictional scenario. Meridian Growth Partners held 12,000,000 shares in Larkfield Instruments, a listed scientific equipment maker, representing about 18% of the company. Rather than drip-feed the position into a market that traded 300,000 shares a day, which would have taken well over a year, Meridian chose an accelerated bookbuild.
The bank launched the book after the close with the shares at $44.00 and guided a range of $41.00 to $42.50. Demand was strong enough to price at $42.00, a 4.5% discount, raising 12,000,000 x $42.00 = $504,000,000 gross. Larkfield's share price opened the next morning at $42.60 and had recovered to $43.90 within three weeks.
Larkfield's management had been briefed the previous week and used the moment well. They published a short statement welcoming the broadening of the register, and their investor relations team arranged meetings with the eight new institutions that had bought the largest allocations. Twelve months later the share register was considerably more diverse, and the daily traded volume had roughly doubled.
Watch out
Common mistakes
- Reading a block trade as a signal that something is wrong at the company. Most blocks reflect the seller's own liquidity needs, fund life or portfolio rebalancing rather than any view on trading.
- Assuming the discount is a loss. The discount is the price of speed and certainty, and attempting to sell the same stock slowly on the market can easily cost more in impact.
- Confusing a block trade with a new share issue. A block trade moves existing shares between investors and raises no money for the company, so there is no dilution.
Questions
People also ask
What is the difference between an agency block and a bought deal?
In an agency block the bank finds buyers and takes no price risk, while in a bought deal the bank buys the shares itself and carries the risk of reselling them.
Why are block trades usually done overnight?
Pricing after the close and before the next open limits the time the market has to move while the book is being built, which reduces risk for both the seller and the bank.
Does a block trade have to be reported?
Yes in most regulated markets, though rules often allow a short publication delay so that the party carrying the position can manage its risk.