Jonathan Weil explains why zombie banks are so hesitant to write off worthless assets in his column, “Financial Frankness Is A Bad Dream For A Bank:”

There’s a simple explanation for why the world’s zombie banks remain so reluctant to write off worthless assets and tap the equity markets for fresh capital. They don’t want to end up like UniCredit SpA.

This month has been a nightmare for the Italian bank’s shareholders. Since embarking last week on a 7.5 billion euro ($9.7 billion) stock sale at a steep discount to its Jan. 3 closing price, UniCredit shares have fallen 39 percent to 2.56 euros. It seems no good deed goes unpunished when it comes to lenders besieged by Europe’s debt crisis. A little bit of candor about the true state of a company’s finances can hurt a lot.

That undoubtedly is the message some other lenders facing large capital shortfalls will take from UniCredit’s troubles. The incentive now, just as most banks are undergoing their year- end audits, will be to stick with the pretense that all is well and there’s no need to raise additional capital.

Not that a lot of them have better options. There’s only so much private-sector capital available to go around. As sickening as the plunge in its share price may be, UniCredit secured an early-mover advantage by acting when it did. Even that might not be enough to ensure its survival without a taxpayer rescue.