| It's essentially a distillation of underwriting standards, low/zero central bank interest rates, and consumer behavior. Underwriting standards for mortgages are typically based on loan to value (LTV) and debt to income. In that calculating, value is traditionally defined as "what the market currently values comparable assets at" (aka comps). For debt, providers of credit (banks and the central mortgage agencies) are more concerned with ability to repay, rather than absolute debt. Consequently, monthly payment >> total price. Therefore, in business as usual (moderate to high interest rates), there are caps on how much individuals can leverage with mortgages (i.e. eventually their LTV or debt to income will exceed standard limits and they'll be denied a mortgage). Unfortunately, both of those key components are heavily influenced by central bank interest rates. If the Fed decides to plunk the rate at 0%, mortgage rates decrease as well. Because mortgage rates have decreased, my resulting monthly payment for the same total loan value decreases. Or, conversely, the total loan value I can assume for a given monthly payment increases. Because it increases, I can pay more for a house. And either I, or someone else does! Now, a few months later, someone else wants to buy the 2nd house on the block. They call out an appraiser, who turns the crank on their standard process, looks at comps in the neighborhood, and values the 2nd house in light of the 1st home sale. Because that 1st sale was inflated (inasmuch as we can judge), the valuation on the 2nd house is likewise inflated. Ultimately, both of these have the end result of raising the cap on how much borrowers can "afford" to pay (assuming static income) for the same asset. Whereby the financial system previously capped their effective leverage at one level, now it's allowing greater leverage (albeit greater leverage that "looks" like the same value, because the underlying inputs have changed). Tl;dr - The financial system used to impose a cap on how much I could pay and qualify for a standard mortgage. Because of actions taken by central banks and consumer behavior, that financial system-imposed cap has effectively been lifted. Now, the consumer themselves is the primary brake on overpaying. And average consumers? They don't math too good. |