What is the term for a trade of less than 100 shares?

A trade of less than 100 shares is called an odd lot.

The term comes from the traditional “round lot,” a standard trading unit of 100 shares. Any order smaller than that standard—such as 37 or eighty shares—was treated as an irregular, or odd, lot. Odd lots became especially common among individual investors, who might buy only a few shares rather than a full standard unit.

Odd-lot orders are not the same as market orders. A market order describes how an order is executed, while odd lot describes its size. A block trade is a very large transaction, and a round lot is the standard 100-share unit in the traditional U.S. convention.

Modern electronic markets can handle odd lots routinely, and market rules may define standard lot sizes differently for particular securities or venues. The quiz’s less-than-100 wording reflects the classic U.S. stock-market definition.