Tag Archives: DeptofNumbers

DofN: Real Home Prices and Real Borrowing Costs Since the Bottom

Real Home Prices and Real Borrowing Costs Since the Bottom


previously showed that continuously declining interest rates since 1980 have been a boon to the buying power of homeowners despite stagnant incomes. After the bursting of the housing bubble last decade and subsequent fall in home prices, the historically low interest rates that followed led to remarkably low payments for borrowers who could still qualify for mortgages these past few years. But we’ve long since put in a bottom for home prices. According to Case-Shiller’s 20 city aggregate that bottom came in February of 2012.

The chart above shows the change in real home prices (blue line) since the bottom. After February 2012 home prices began to rise while mortgage rates continued to fall. They fell enough in fact that their declines offset the rise in real home prices for another 8 months. That is, a borrower could obtain a lower mortgage payment via falling borrowing costs despite rising home prices. The bottom in terms of a monthly mortage payment didn’t come till October of 2012. The red line shows how mortgage payments have changed since then.

In short, real home prices have risen about 17% since the February 2012 bottom, but the real price in terms of borrowing costs have risen just over 26%. I don’t expect rates to leap in the near future, but if rates continue to rise with Fed tapering (they’re up about one percentage point from the bottom) it could have a notable impact on affordability for first-time buyers. On the other hand, low existing home inventory suggests there hasn’t been a significant falloff in demand yet and mortgage rates have been trending down again recently as well.

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DeptofNumbers: Growth in Mortgage Purchasing Power

Growth in Mortgage Purchasing Power


Above is a chart of real median household income and the real purchasing power of the same median household income when utilizing a 30-year mortgage. Said another way, if you kept the fraction of real median household income going towards a mortgage payment the same (say 30%), the red line shows the growth in what you could buy with your payment.

The chart highlights the dramatic rise in purchasing power of the median income household despitethe lack of growth of the median household’s real income. Growth in the capacity to borrow has replaced income growth over the last 30 years. Of course this is possible because interest rates have been falling continuously since the early 1980s making it feasible to borrow more and more with less income.

If we wanted to increase purchasing power in an environment where interest rates were not in decline, we’d need to see a substantial increase in real median income. For instance, say 30-year mortgage rates were at 6.5% instead of their recent level of roughly 3.5%. All else being equal, to get the same purchasing power as a 3.5% mortgage rate with a mortgage rate of 6.5% would require a 41% increase in real income! 1 Clearly (and by design in recent years), record low mortgage rates are a huge stimulus for home prices.

What happens when the 30+ year secular decline in interest rates ends? Even if rates stay low, the stimulus of declining rates on asset prices (homes in particular) will disappear. While incomes will likely increase over the next few years, we’ve already seen how much they would need to increase to match the purchasing power effects of falling interest rates. And if interest rates rise even modestly, purchasing power will be significantly curtailed. How home prices, under the additional influences of inertia and psychology, actually respond is another matter.

1. Assuming again that a borrower would want to spend the same fraction of their income on a mortgage payment regardless of the interest rate environment. 

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