Dr. Mike Walden, North Carolina Cooperative Extension economist in the College of Agriculture and Life Sciences at N.C. State University, responds:

"It's a concept that relates to how investments are valued at any point in time. And what mark to market says is investments must be valued at their current worth or their current sales value instead of their original value. Let me give you an example. Let's say a bank makes a $100,000 mortgage loan. Now if it works out, the bank will get back its $100,000 plus interest. But due to the poor housing market today and due to the fact that perhaps the house on which that loan was made has actually now fallen in value, if the bank tried to sell that loan at this moment, it perhaps could not get back the $100,000. It could get back something less, maybe $60,000. Well, that $60,000 is the mark to market value. And this is a relatively new rule, but critics have said that is has resulted in the big drops that we have seen in the investment value of bank's portfolios, which has led to the credit crisis, led to the $700 billion rescue, etc, etc. Now supporters say, no it doesn't matter. Mark to market does give you a true value, and that is what you want to see. So this is going to be an ongoing debate, but clearly mark to market has moved to the head of the financial discussion."