Liquidity Preference, Opportunity Costs, and Arbitrage: Home Mortgage Edition

I was at a social outing last week, and during the conversation the subject turned to mortgages. The host averred his strong preference for not carrying a mortgage. “Just pay it off, and then you don’t have to worry about making that payment every month. Besides, I can’t stand paying all that interest every year.”

Now, most Americans do not have the wherewithal to pay off their mortgage 100%. Indeed, for most people paying off a car loan would be a stretch. But I could, and yet I continue to carry both a car loan and a home mortgage. So I thought I would write about why it can be a good idea to continue carrying debt, when you have enough assets to pay it off.

First and foremost, cash keeps your options open. Let’s say you have $100,000 in debt. Also suppose you have $100,000 in cash. You could extinguish all of your outstanding debt. But then, you would no longer have any cash on hand. You better hope the transmission in your car doesn’t go out, or the roof doesn’t leak, or any of a hundred possible contingencies does not occur. Because then you’ll wish you had held on to more of that cash.

The desire to keep cash on hand to cope with life’s curve balls is what finance professors call liquidity preference. Personal finance experts recommend you keep three to six months worth of cash on hand for just that reason. Okay, but going back to our hypothetical example, unless you’re a member of the 1%, you probably do not need $100,000 on hand to fund your lifestyle for six months, or even a year. Why not pay down the mortgage?

You give up the chance to do something better with the money, what economists call opportunity costs. Let’s run a more complicated version of our original scenario. This time we’ll start from the same place: a $100,000 mortgage and $100,000 in cash. Now we decide to hold $50,000 in cash for emergencies. We can use our remaining $50,000 in one of two ways. We can either pay off $50,000 of our mortgage, or we can pay $50,000 of Verizon stock. Verizon currently has a dividend yield of 5.15%, so our fifty grand would give income of $2575 a year. There is a little risk with holding the stock, but unless people stop making phone calls it is a pretty safe bet.

For the mortgage, assume a 15 year fixed rate mortgage at 3.5%. If you borrow $100,000, you will pay $3418 in interest the first year, and have dividend income of $2575. The net cost of the borrow and invest strategy is $843.

If you down debt and only have a $50,000 mortgage, you will pay $1709 interest the first year. Paying down debt will cost you $866 over the alternative strategy. Since the interest payments will drop each year of the mortgage, but the dividend payment should remain constant, the borrow and invest strategy will outperform the pay down debt strategy by a greater amount every year. By the fifth year, you will be $1152 ahead with the borrow and invest strategy.

Borrowing at a low interest rate and investing at a higher rate is an example of arbitrage, and it is one of the ways that the big boys on Wall Street earn their huge bonuses. They add a lot more zeroes to their numbers, of course.

I’m not saying you shouldn’t pay down debt, and there is something to the psychological lift you can get from not owing any money. But being debt free is not necessarily the best strategy for maximizing your financial well being.