Which Bonds Are Mortgage Rates Tied To?

Posted by Leslie Bauer on Thursday, May 27th, 2010 at 6:08pm.

Rates on mortgage loans up to $417k and up to $729k are tied to trading in “agency” mortgage-backed bonds—meaning bonds issued by Fannie Mae, Freddie Mac, and Ginnie Mae. So while many look to the 10yr Treasury Note for clues on mortgage rates, they should be looking at mortgage bonds. And specifically, there are different duration mortgage bonds to watch during different times in the market to predict what rates might do, and how to properly lock a rate at the best time.

Prices on agency mortgage bonds have been slightly abnormal lately, so we have to look at the security price difference between a 4% and a 4.5% security to see what’s going on. Historically, on average, price differences between .125% for a 30-yr mortgage is about .5 in price, or 2 points for .5%. This relationship, however, has gotten out of whack with the latest volatility and prepayment fears in the mortgage-backed security sector. Currently the price difference between a 4.0% security and a 4.5% security is now 2.75 in price (instead of 2.00), so therefore the difference in price between a 4.75% loan, which would typically be slotted into a 4.50% security, and a 4.625% loan, which would go into a 4.00% security, same impounds, same LTV, same credit score, is now much greater.

With FNMA 4.5’s around 102 (a 2 point premium) and FNMA 4’s trading near par, everyone is in uncharted territory – and the mortgage market is roiled. Low coupon product, now trading near par, has not yet been originated in any kind of volume that helps liquidity. News yesterday out of Spain, that Spain’s central bank had to prop up a regional bank, did not help the stock market, and stock prices are back down to early February levels. Bond prices also worsened, with traders attributing that to some profit taking by investors. And this morning the markets are not only spooked by Europe, but now also by some tension coming out of Korea – just what we need. The 10-yr is down to 3.11% ahead of the $42 billion 2-yr auction ($40 billion 5-yr’s tomorrow, $31 billion 7-yr’s Thursday) and mortgages are better by about .250.

via thebasispoint.com


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