Between 2003 and 2006, the Federal Reserve raised rates by 4.25%. Yet it was precisely during this period that the housing boom accelerated, fueled by rapid growth in mortgage lending. There is deep disagreement about how, or even if, monetary policy impacted the boom. Using differences in exposure to the deposits channel of monetary policy, we show that Fed tightening induced a large reduction in banks’ deposit funding, which led banks to contract portfolio mortgage lending by 32%. However, this contraction was largely offset by substitution to privately-securitized (PLS) mortgages, led by nonbank originators. Fed tightening thus induced a shift in mortgage lending away from stable, insured deposit funding toward run-prone and fragile capital markets funding with little impact on overall lending. We find similar results during the most recent tightening cycle over 2014–2017 when PLS lending reemerged.

2003 年至 2006 年间，美联储将利率提高了 4.25%。然而，正是在此期间，在抵押贷款快速增长的推动下，房地产繁荣加速。关于货币政策如何或是否会影响繁荣存在严重分歧。利用货币政策存款渠道敞口的差异，我们表明美联储紧缩政策导致银行存款资金大幅减少，导致银行收缩了 32% 的投资组合抵押贷款。然而，这种收缩在很大程度上被非银行发起人领导的私人证券化 (PLS) 抵押贷款的替代所抵消。因此，美联储紧缩政策导致抵押贷款从稳定、有保障的存款资金转向易运行且脆弱的资本市场资金，而对整体贷款几乎没有影响。