Every once in a while over the last decade or so I have heard about Black Monday, where mysteriously, the stock market dropped dramatically in October of 1987. The DOW dropped 22.6% in a single day. Which is a lot. I just ran across a very interesting academic papers that claims to know its cause—taxes (of course!).

Sitting in the Tax Museum is a stack of losing lottery tickets.  It is a good three inches tall. I bought these tickets on eBay.  Why can one buy losing lottery tickets on eBay?  The answer, as is the answer to every interesting question, is, of course, taxes.  If you have made money gambling, you can deduct any gambling expenses up to the amount of income you generated.  So, for $10, you could buy $1,000 worth of losing lottery tickets, and so would be able to show fraudulent evidence of $1,000 of expenses to shield $1,000 of your gambling winnings.
This fact, in itself, is interesting, but what does the existence of a market for a very specific tax evasion instrument tell us about the world?  I decided to investigate.