[throwaway2037]

To be clear, interest rate derivatives (futures, swaps, [edit] options, etc.) are very important for banks and corps to manage their interest rate risk. By definition, these are zero sum products.

Also, economists would not term the stock market as zero sum game. All boats can and do rise together. Look at the S&P 500 index since the 2008 GFC. Spectacular success that reflects the wider US economy.

[gomerspiles]

Sure, the stock market is clearly grounded in a positive sum game of enabling more investment options. Things like whether to penalize day trading for its zero sum aspects or appreciate it for side effects are an argument in legislation/regulation debates.