lost more than $5 billion in the fourth quarter as bad credit ate into its investments the company said Thursday. NEW YORK—American International Group Inc. the largest insurer in the U.S. AIG has been thrust to the forefront of the credit crisis gripping financial markets by contracts known as credit default swaps. Another important benefit of refinance mortgage loans is that gives the borrower more flexibility. It allows you to change terms from a long one to something shorter. In this way, you can pay off the principal more quickly, thus saving you from the total interest charges.