Concerns over the banking sector are currently making things rough in the $8 trillion agency mortgage bond market. Agency mortgage bonds are widely held by banks, bond funds, and insurers as they are backed by mortgage loans from government-controlled lenders Fannie Mae and Freddie Mac. They are far less likely to default than most debt. They are also easy to buy and sell quickly, which is why they were Silicon Valley Bank’s biggest investment before its troubles. However, agency mortgage bonds are vulnerable to rising interest rates like all long-term bonds. This pushed their prices down last year and also saddled banks such as Silicon Valley Bank. In fact, the risk premium on a widely followed Bloomberg index of agency MBS hit its highest level since October last week, as climbing interest rates led to volatile global markets. According to bond fund managers, this certainly reflected fears that other regional banks might have to sell their holdings. When benchmark interest rates rise, bonds that were sold at times of lower rates lose value. For instance, prices of low-coupon agency mortgage bonds started dropping about a year ago, when the Fed raised interest rates to tame inflation and also indicated that it might start selling the mortgage bonds that it owned.

Finsum:With faltering banks such as Silicon Valley Bank holding large amounts of agency mortgage bonds, the turmoil in the banking industry is roiling the $8 trillion agency mortgage bond market.