Are these five banks hiding more than $140 billion in losses?

Jonathan Weil at Bloomberg has quite a contention: on a mark-to-market basis, a number of banks -- such as Regions Financial (RF), SunTrust Banks (STI), and KeyCorp (KEY) -- would have negative regulatory equity. Meanwhile, others -- including giants like Bank of America (BAC) and Wells Fargo (WFC) -- would be insolvent or undercapitalized, with hidden loan losses of more than $140 billion. In a world blind to "too big to fail," the former group would be shuttered by the FDIC, and the latter would either need to raise capital or risk a similar fate.

As Weil correctly points out, footnotes disclosing the fair market value of loans on Regions' balance sheet show a $22 billion gap between the value currently carried on the books currently and the price that they could be sold for. At quarter's end, this exceeds stockholders equity of $18.7 billion. However, accounting and regulatory rules allow those loans to be labeled as "held to maturity," meaning that they are excluded from being marked-to-market -- thus leading to two different values that can paint drastically different pictures of a bank's health.