在了解这两个词汇前我们需要先学习一个概念：Stock Split（拆股）。

拆股，又叫做分割股票。在股票证券市场，拆股是指将一股面额较高的股票交换成数股面额较低的股票的行为，但它不属于股利。拆股后，发行在外的股数增加，每股面额降低，每股盈余下降；公司价值、股东权益总额、股东权益各项目的金额及其相互间的比例保持不变。也就是说，通常情况下拆分股票不会影响企业市值，也不会改变企业基本面，只是降低了股票购买门槛，吸引更多人买入。

明白了这个之后我们看下这两个词汇的英文含义：

Forward split

A forward stock split can add to the number of stocks you own, but it does not increase your investment value.

Reverse split

If a company announces a reverse stock split for shares you own, it means that instead of giving you additional shares, the company will merge your shares and reduce the number of shares you own.

A reverse split reduces the overall number of shares a shareholder owns, causing some shareholders who hold less than the minimum required by the split to be cashed out.

拆股分为正向拆股（Forward split）和反向拆股（Reverse split）。正向拆股（也称为规范拆股或直接拆股），拆股后会比拆股前有更多的股份数。拆股基本上大多数是正向拆股。例如，“1拆2”时，股东持有100股，在拆股后股东的持股数会增加100股股票，即此时该股东持有200股，相反，如果是反向拆股，则会减少股东的持有股数。

另外，拆股将会产生散股拆股（odd lot-generating split），比如，“2拆3”时，小股东就有持有散股，100股变成150股。反向拆股会使一批小股东的股份被取消。一间上市公司频繁的正向拆股和反向拆股，常常被市场认为公司试图在寻找合适的交易价位。

In some ways, the effects of forward splits seem beneficial: equity value increases, trading volume increases, and the number of shareholders increases. In other ways, the effects of forward splits seem less desirable: shareholder risks increase, and some transaction costs, such as bid-ask spreads, are higher after forward splits.

在某些方面，正向拆股的影响似乎是有益的：股权价值增加，交易量增加，股东数量增加。在其他方面，正向拆股的影响似乎不太理想：股东风险增加，一些交易成本，例如买卖差价，在正向拆股后更高。

In recent years, perhaps a consequence of the Internet bubble burst, a new type of reverse splitting firm has emerged. In the months preceding the bubble burst, the initial public offering (IPO) market was at its peak. New technology-based and Internet-based firms were in high demand. After the bubble burst, many of these technology and Internet start-up firms lost a large percentage of their market value and their stock price fell below the minimum bid price required for continued listing.

近年来，或许是互联网泡沫破灭的结果，出现了一种新型的反向拆股公司。在泡沫破灭前的几个月里，基于新技术和互联网的公司需求量较大，首次公开募股 (IPO) 市场处于顶峰。泡沫破灭后，许多科技和互联网创业公司市值缩水，股价跌破继续上市所需的最低投标价。