There are lots of things to worry about in the world and somewhere on the list is the fact that, while yields on agency mortgage-backed securities are really really really low, the rate you’ll pay for a new mortgage is only really low, so a couple of reallys have fallen off a truck somewhere. This worry isn’t at the top of my personal list – my mortgage rate is low enough I guess? – but it seems to make many other people’s list for two intersecting reasons. First, if the primary desire of Fed policy is to get people to buy houses, be rich, etc., and if its primary mechanism for doing so is buying MBS, then the inefficiency in transforming that mechanism into that desire is rather macroeconomically important and bad. Second, if money is coming out of the Fed and not ending up in homeowners’ pockets, that leaves only so many pockets it could be ending up in, and it is easy enough to observe that big banks (1) sit between the Fed and the homeowners and (2) have lots of pockets. So you can see how it might be fun to worry about money going to big multipocketed banks, because if it does, you get to be mad at them.
Anyway the New York Fed is doing a conference on it today; here’s the background paper and it’s really interesting; I recommend it, particularly if, like me, you have a hazy understanding of agency mortgage securitization. Everything in this space is predicated on somewhat fake math but their math is less fake than the simple spread math, which basically assumes that banks make a profit of:1
- Annual Profit = Mortgage Rate – MBS Yield
By that math, as William Dudley points out, the spread was 30-50bps in the ’90s and early 2000s, but rose to 150bps in September and is around 120bps now. The Fed’s paper, on the other hand, walks through the actual securitization process to get cash flows into and out of the mortgage lender, and computes its profit (technically, profit plus non-interest-y costs like underwriting and hedging) as roughly:
- Up-Front Profit = Sale Price Into MBS – Origination Price + 4 x (Mortgage Rate – MBS Coupon – GSE Guarantee Fee
Why 4? I dunno it’s in the paper.2 Anyway by this measure here is what has happened in the world: Read more »