应该是cmbs吧。cmbs ** short for commercial mortgage-backed securities,which ** a kind of mbs.mbs ** a fixed income security or debt instrument,whose cash flow ** based on the mortgage payment on a pool of loans.cmbs ** specifically collateralized by loans which are secured by commercial real estate mortgages.cmbss are usually **sued by secondary mortgage market makers(eg.large banks)to pool ex**ting mortgage loans together and sell the new security to cmbs investors as bonds.what the banks essentially do ** to transfer the r**ks of mortgage loans of property buyers to the cmbs investors.so it the property buyer cannot make interest and principal repayment,the cmbs investors would suffer the loss,not the banks that loaned the money in the way of mortgage. 简单说来,cmbs基本上就是银行把商用房地产抵押贷款打包,然后作为债卷一样出售给投资者。这样银行贷款给买房者的风险就转移到投资者身上,而且银行在卖出cmbs的同时收入现金,而贷款从银行的资产负债表中消失。其后银行作为cmbs的管理者还可以源源不断的收入服务管理费。而投资者则多了很多的投资机会,所以mbs在us交易非常活跃。