The returns to foreknowledge like this are infinite, so I impose some limits. There is no investing in individual stocks or securities, no trading through the year (the trades placed on New Year’s Day must stay in place throughout), and no leverage. They can, however, sell short to benefit when prices go down. Because they are such a prestigious client, they’re also able to trade without incurring any costs at all.There are also limits on their foresight. They have to be able to show a coherent rationale for their trades at the beginning of January. Betting on the results of unpredictable natural disasters, for example, is out. And they’re required to make trades across a spread of asset classes and geographies; they can’t just make variations of the same bet in the same market.