Shared appreciation mortgages (SAMs) feature mortgage payments that adjust with house prices. They are designed to stave off borrower default by providing payment relief when house prices fall. Some argue that SAMs may help prevent the next foreclosure crisis. However, home owners' gains from payment relief are mortgage lenders' losses. A general equilibrium model in which financial intermediaries channel savings from saver to borrower households shows that indexation of mortgage payments to aggregate house prices increases financial fragility, reduces risk‐sharing, and leads to expensive financial sector bailouts. In contrast, indexation to local house prices reduces financial fragility and improves risk‐sharing.

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SAM的财务脆弱性？

共享增值抵押（SAM）具有随房价调整的抵押付款。它们旨在通过在房价下跌时提供付款减免来避免借款人违约。有人认为，SAM可能有助于防止下一次止赎危机。但是，房主从付款减免中获得的收益是抵押贷款人的损失。金融中介机构将储蓄从储蓄者转移到借款人家庭的一般均衡模型表明，按揭付款与总房价的指数化会增加金融脆弱性，减少风险共担，并导致昂贵的金融部门救助。相反，对当地房价进行指数化可以减少财务脆弱性，并提高风险分担。