这一词理解上的主要难点在于spread一词。

Spread在这里指的是利差，是指诸如债券或国库券等现货金融工具所带来的收益与该项投资的融资成本的差额。利差，顾名思义，就是利率之差。相应的比如有Credit spread，信用利差也称为质量利差(quality spread),是指除了信用等级不同，其他所有方面都相同的两种债券收益率之间的差额，它代表了仅仅用于补偿信用风险而增加的收益率。

理解spread之后，这个词就很容易理解了。

“excess spread”即为超额利差。超额利差是信用卡应收款组合收益减去向投资者支付的利息、相关服务费用和其它信托费用以后的余额。这部分超额利差将首先用来为当期被注销的应收款提供资金，以保证将应收款余额维持在某一水平。弥补完损失后剩余的超额利差将被存人超额利差账户。是最常采用的内部信用增级手段。它首先被用来为投资者提供对应收款违约所造成的损失的“缓冲”。Excess spread is the surplus difference between the interest received by an asset based security's issuer and the interest paid to the holder. When loans, mortgages, or other assets are pooled and securitized, the excess spread is a built-in margin of safety designed to protect that pool from losses.

以下为相关双语示例，供参考：

The excess spread (excess interest rate) on high-yield corporate bonds has fallen from more than 16 percentage points at the start of 2009 to less than six points. 

高收益公司债券的超额利差（超额收益率）从2009年初的16%点多下跌到不到6点。

If the excess spread is not used to absorb losses, it may be returned to the originator or held in a reserve account. 

如果超额利差不用于承担亏损，则就有可能被退还发起人或置于准备金账户中。