Block Trade

A block trade is a single transaction involving an unusually large quantity of shares, bonds, derivatives or crypto, negotiated privately between parties rather than executed piece by piece on a public exchange. Block trades are used by institutional investors such as pension funds, asset managers and hedge funds that need to buy or sell large positions without moving the market price against themselves. They are usually arranged by brokers or investment banks through specialised block trading desks.

Because publishing a huge order on an exchange would signal intentions and cause prices to move, block trades are often executed off the main order book, through negotiated deals, dark pools or privately agreed prices that are then reported to the market. In the United States, a block of shares has traditionally been described as at least 10,000 shares or a value of at least $200,000, though exchanges and regulators use different thresholds for different products. In crypto, the equivalent service is provided by over-the-counter desks.

Imagine a farmer who needs to sell an entire year's harvest of potatoes at once. If he tipped them all onto a market stall, the sudden glut would crash the local price and he would get very little per sack. Instead, he quietly phones a large wholesaler and agrees a single price for the whole lot, perhaps slightly below the market rate, and the potatoes move in one go.

A block trade is the investment world's version of that phone call. A big investor who wants to sell millions of shares, or a large amount of bitcoin, arranges one deal with a buyer through an intermediary. The price is agreed privately, and the market only learns of it afterwards, reducing the disruption the sale would otherwise cause.

There are several common methods:

• Principal trades. A bank or broker buys the whole block from the seller at an agreed price, taking the risk of reselling it, and is paid through the discount it negotiates.
• Agency trades. The broker finds one or more buyers for the block without taking ownership, earning a commission.
• Accelerated bookbuilds. For large stakes in listed companies, banks contact institutional investors overnight to sell shares quickly at a discount to the last price.
• Dark pools and crossing networks. Electronic venues that hide orders until they match let large buyers and sellers meet anonymously.
• Exchange block facilities. Futures exchanges allow privately negotiated block trades above minimum sizes, which are then reported and cleared through the exchange.

Block trades are usually priced at a discount to the market for sales and at a premium for purchases, compensating the counterparty for taking on a large position and the risk that prices move. The size of the discount depends on the stock's liquidity, its volatility, the size of the block relative to normal trading volume and market conditions. When a block sale is announced, especially by a major shareholder, the share price often falls as investors assess whether more sales are coming. Large trades can also be broken into smaller pieces and executed through algorithmic trading over hours or days, an alternative to a single block.

Block trades are subject to market rules on fair dealing, best execution and reporting. Trades must generally be reported to the market within set time limits, though regulators may allow delayed publication of large trades to protect the parties from being exploited. In Europe, MiFID II includes "large in scale" waivers that allow certain large orders to avoid pre-trade transparency. Information about an upcoming block is highly sensitive: brokers who use it to trade ahead of the client engage in front-running, and leaking a client's plans can breach market abuse and insider trading rules. Several banks have been fined in recent years over how they handled information in block trades.

Large crypto trades are commonly handled by OTC desks run by exchanges, brokers and trading firms, which quote a single price for a large amount of bitcoin, ether or stablecoins and settle directly between the parties. This avoids slippage on public order books, which can be thin for all but the largest coins. Derivatives venues offer block trading for options and futures, and some regulated exchanges such as CME allow privately negotiated block trades in their crypto futures. Crypto OTC trades face the same concerns as other markets, including counterparty risk and settlement risk, along with anti-money laundering checks on the source of funds, especially for very large transactions. The wider market for these deals is described in Crypto OTC.