“碎股”又称“散股”“零股”。“碎股”一词，是指不足一手（最低交易单位）的股票。在香港买卖股票，最小的交易单位为一手（one lot），而一手股票有多少股，就要视乎个别股票而定。例如汇丰控股（0005），一手便要400股。如果投资者要买汇丰的股票，最少要一手，即400股。长江实业（0001）、新鸿基地产（0012）及恒基（0016）等，则一手要1,000股。而大部分二线股、三线股，每手便要2,000股。至于认股证等衍生工具，有些一手甚至要10,000股。

碎股的出现，通常因为股本结构有所改变。例如公司在宣布业绩及派息时，同时宣布送红股（bonus shares），所送红股就很容易会变成碎股。

假设某股份一手是1,000股，该股宣布十送一红股；如果投资者持有一手股份，那么他就可以获得100股红股，但这100股红股便成了碎股。究竟投资者是否可以把这些碎股在市场上沽售？答案是可以的。虽然在联交所买卖的股份是以一手为单位，但市面上也有一些公司是专门收购碎股，当然所付出的收购价会较市价略低，例如低五至十个价位，但投资者却能借此售出碎股套现。而收集碎股的公司，当收集碎股的数目达至一手时，便可化零为整，以较高的价格在市场上沽出。

一手为one lot，碎股为odd lot。

英文释义如下：

An odd lot is an order amount for a security that is less than the normal unit of trading for that particular asset. Odd lots are considered to be anything less than the standard 100 shares for stocks. Trading commissions for odd lots are generally higher on a percentage basis than those for standard lots since most brokerage firms have a fixed minimum commission level for undertaking such transactions.

Odd lots may inadvertently arise in an investor's portfolio through reverse splits or dividend reinvestment plans. For example, a one-for-eight reverse split of a security, of which the investor holds 200 shares, will result in a post-split amount of 25 shares. While trading commissions for odd lots may still be higher than for standard lots on a percentage basis, the popularity of online trading platforms and the consequent plunge in brokerage commissions means that it is no longer as difficult or expensive for investors to dispose of odd lots as it used to be in the past.

使用场景可参考如下双语例句：

Odd lot trading is only applicable to sale orders but not purchase orders via "Market Order".

只可以「市价盘」沽出碎股，并不可以「市价盘」买入碎股。

In order to alleviate the difficulties arising from the existence of odd lots of the Consolidated Shares and the change in board lot size, the Company has appointed Metro Capital Securities Limited as an agent to provide matching service, on a best efforts basis, for the sale and purchase of odd lots of Consolidated Shares arising from the Share Consolidation.

为减少存在合并股份碎股及更改每手买卖单位所产生之困难，本公司已委任美高证券有限公司作为代理，按尽力基准为买卖自股份合并产生之合并股份碎股提供对盘服务。

For the purpose of this Article “shares” shall mean shares of all classes and securities which carry a right to subscribe or purchase, or are otherwise convertible into, shares of the Company and an “odd lot of shares” shall mean a number of shares less than the usual number authorised for trading on a stock exchange in Hong Kong.

就本条文而言，“股份”包括任何类别附有认购或购买权利或可转换为公司股份的股份及证券及“碎股”是指少于香港联交所授权可交易的股份数量。