Definition of 'Bunching'
The combining of odd-lot or round-lot orders for the same security so that they can be executed at the same time. Bunching occurs when traders and brokers combine small or unusually-sized trade orders into one larger order. If an order is bunched, all affected clients must agree to the bunching before the order is submitted.
Investopedia explains 'Bunching'
Bunching can be financially advantageous for investors with orders for less than 100 shares of a particular security, who would otherwise be charged extra fees for the odd-lot order, sometimes called an odd-lot differential. Odd-lot orders are difficult to match, and additional fees are common. Often, bunching occurs on the floor of an exchange when multiple round-lot orders or odd-lot orders are combined into one trade execution.
The term bunching also refers to a pattern that appears on a ticker tape when a series of same-security trades print one after the other.