Well its supposed to be "Quad Witching", the expiration of all the index and commodity options and futures.

But today its "Wicked Witch" instead, and if you were a bad boy and didn't pay your taxes, its also a day when you are likely sweating bullets:

"Both men were accused of creating bogus trusts and sham offshore entities to hide some $20 billion in offshore assets owned by wealthy American clients. UBS is in talks with the Justice Department and Swiss authorities about turning over the names of up to 20,000 American clients.

Mr. Birkenfeld’s work concerned offshore undeclared assets held for wealthy Americans. In his statement of facts, he said that he and other unidentified UBS private bankers urged their American clients to destroy all offshore private banking records held in the United States; to use Swiss credit cards that could not be discovered by American tax authorities; and to falsely characterize money pulled out of Swiss accounts as loans from UBS.