ClawBack Mechanism指的是回补机制， 是专供新股上市时用的一项机制。《上市规则》规定，主板公司招股时，配售及公开发售比例至少是9比1。若散户需求大，譬如公开发售获15至50倍认购，回补机制便可发挥作用，把配售及公开发售比例调节至7比3；若获50至100倍认购，比例将调整至6比4；逾100倍认购，比例则是五五之比，以保证公众人士能获得足够的新股认购额。

其英文释义如下：

Where an IPO includes both a placing tranche and a public subscription tranche the minimum allocation of shares to the subscription tranche shall be as follows:

– an initial allocation of 10% of the shares offered in the IPO;

– a claw-back mechanism that increases the number of shares to 30% when the total demand for shares in the subscription tranche is 15 times but less than 50 times the initial allocation;

– a claw-back mechanism that increases the number of shares to 40% when the total demand for shares in the subscription tranche is 50 times but less than 100 times the initial allocation;

– a claw-back mechanism that increases the number of shares to 50% when the total demand for shares in the subscription tranche is 100 times or more the initial allocation.

相应的，回补机制中回补的股份即称为“回补股份”，以下为相关示例：

In the event of a reallocation of Offer Shares from the International Placing to the Hong Kong Public Offering pursuant to Clauses 4.11.1 and 4.11.2, the relevant number of International Placing Shares shall be withdrawn from the International Placing and made available as additional Hong Kong Offer Shares offered for subscription pursuant to the Hong Kong Public Offering (the “Clawback Shares”).

在按照第4.11.1和4.11.2条将发售股份从国际配售重新分配至香港公开发售的情况下，相应数目的国际配售股份应从国际配售中退出，并作为额外的香港发售股份公开认购（“回补股份”）