After a brief interlude of hope at the start of August, investors across US fixed-income markets are once more shunning risky assets and preparing for more bad news as banks close their books for the third quarter.

Much of the risk aversion seen this week has stemmed from renewed worries about the US government having to step in and assume greater responsibility for Fannie Mae and Freddie Mac, who as government-sponsored enterprises own or guarantee roughly half of the outstanding US home loans.