The pressures were already immense when David B. Kellermann was promoted to the top financial position at the mortgage giant Freddie Mac last September. Then they got even worse. Mr. Kellermann’s boss and other top executives were ousted when the Treasury secretary seized Freddie Mac and its sibling company, Fannie Mae; others left on their own and were not replaced. Soon President Obama told the companies they were responsible for carrying out some of his programs to revive the economy, in addition to keeping the housing market afloat by buying and selling hundreds of thousands of mortgages a month. Mr....
