This paper studies the links among credit supply expansion, commercial bank asset account structures, and the housing boom preceding the 2007–2009 financial crisis. We propose a real business cycle model with a housing market and financial intermediaries (banks) subject to leverage constraints. In our model, banks channel funds to firms for production and provide collateralized loans to mortgage borrowers; thus, banks determine their asset account structures endogenously. We show that a credit supply expansion to banks can account for four key facts that characterize the housing boom: (1) an increase in real house prices; (2) an increase in the mortgage-to-GDP ratio; (3) a decrease in the real mortgage interest rate; and (4) an increase in the ratio of mortgages to firm loans in commercial bank asset accounts. In our model, a credit supply expansion to banks can also generate a boom-bust cycle through the collateral value channel via mortgage borrowers. Asset-side bank regulations that reduce excessive mortgage issuance during a credit boom can help to dampen the subsequent economic downturn.

本文研究了信贷供应扩张，商业银行资产账户结构与2007-2009年金融危机之前的房地产繁荣之间的联系。我们提出了一个具有房地产市场和金融中介机构（银行）的真实商业周期模型，该模型受杠杆约束。在我们的模型中，银行将资金引导给企业进行生产，并向抵押借款人提供抵押贷款；因此，银行是内生地决定其资产账户结构。我们表明，向银行的信贷供应扩张可以解释住房热潮的四个关键事实：（1）实际房价上涨；（2）抵押贷款占GDP的比例增加；（三）实际抵押贷款利率下降；（4）商业银行资产账户中抵押与公司贷款的比率增加。在我们的模型中 银行信贷供应的扩张还可以通过抵押借款人通过抵押品价值渠道产生繁荣-萧条周期。减少信贷繁荣期间过多抵押贷款发行的资产方银行法规有助于缓解随后的经济下滑。