库存股，也称库藏股，英文表达为Treasury Stock或Shares In Treasury，是指已公开发行的股票但发行公司通过购入、赠予或其他方式重新获得可再行出售或注销的股票。

库存股股票既不分配股利，又不附投票权。在公司的资产负债表（Balance Sheet）上，库存股不能列为公司资产，而是以负数形式列为一项股东权益（Shareholder's Equity）。借方表示增加，贷方表示减少，属于所有者权益备抵项（其他所有者权益科目借减贷增）。库存股在回购后并不注销，而由公司自己持有，在适当的时机再向市场出售或用于对员工的激励。也就是说，公司将已经发行出去的股票，从市场中买回，存放于公司，而尚未再出售或是注销。

相关法律法规：

《公司法》不允许上市公司库存股份。

《证券法》没有就股份回购及回购后的处理方法作出规定。

《股票发行与交易管理暂行条例》第41条规定：

未依照国家有关规定经过批准，股份有限公司不得购回其发行在外的股票。

《上市公司章程指引》规定：

公司购回该公司股票必须在一定时间内注销该部分股份。

参考双语例句：

Rule 7.24(5) is amended to read: “If the proposed open offer would increase either the issued share capital (excluding treasury shares) or the market capitalisation of the issuer by more than 50% (on its own or when aggregated with any other open offers or rights issues announced by the issuer (i) within the 12 month period immediately preceding the announcement of the proposed open offer or (ii) prior to such 12 month period where dealing in respect of the shares issued pursuant thereto commenced within such 12 month period, together with any bonus securities (other than any such bonus securities to be issued into treasury), warrants or other convertible securities (assuming full conversion) granted or to be granted to shareholders as part of such rights issues or open offers):-”.

修订第7.24(5)条为：“如建议进行的公开招股会导致发行人的已发行股本（不包括存库股）或市值增加50%以上（不论单指该次公开招股，或与发行人在下述期间公布的任何其他公开招股或供股合并计算：(i)建议进行公开招股未公布之前的12个月内；或(ii)此12个月期间之前的交易而在此12个月期间开始执行此等供股或公开招股中发行的股份包括授予或将授予股东的任何红股（发行予库存的任何该等红股除外）、权证或其他可换股证券（假设全部转换））：”。

As long as the book value of the retired treasury stock is higher than the sum of its par value and capital surplus on stock issuance, the excess should be debited to other capital surplus or retained earnings when capital surplus-treasury stock is insufficient.

库藏股票之帐面价值如高于面值与股票发行溢价之合计数时，其差额应冲销同种类库藏股票所产生之资本公积，如有不足再借记保留盈馀；库藏股股票之帐面价值如低于面值与股票发行溢价之合计数时，其差额应贷记同种类库藏股票交易所产生之资本公积。

According to the Securities and Futures Commission (91) article 111467, shares previously bought back by listed or over-the-counter traded financial institutions (in accordance with Article 28-2 of Securities Exchange Act), upon conversion of the institutions into wholly-owned subsidiaries of a financial holding company and the conversion of such shares into treasury shares of the financial holding company, must be treated by such subsidiaries as their own treasury shares and a deduction of shareholders’ equity and must be treated as treasury shares of the financial holding company.

本公司依财政部证券暨期货管理委员会(91)台财证(六)字第111467号函规定：金融机构原依证券交易法第二十八条之二第一项规定买回之库藏股，嗣因办理转换成为金融控股公司之子公司，其库藏股依金融控股公司法第三十一条规定随同转换为金融控股公司之股份者，该金融机构仍应将其持股列为库藏股票，作为股东权益之减项，而金融控股公司对该子公司持股亦应视同库藏股处理，若金融机构原係持有其他参与转换金融机构之股份，嗣因办理转换而持有金融控股公司之股份者，应维持股权投资之会计处理，本公司则依财务会计准则公报第三十号“库藏股票会计处理准则”之规定，于认列投资损益及编制财务报表时，应将子公司持有本公司之股票视同库藏股票处理。