"A weak money pump is a money pump that returns us to the same situation that would have happened if we had never traded at all."

Weak money pumps occur all the time in real life. People pay big bucks to let other people manage their money without knowing that they might have been better off doing it themselves. The pump is disguised by normal expected gains (in a well functioning economy), which the stock broker or hedgefund manger can claim was his doing.

Strong money pumps I would think almost as a rule don't exist in individuals (since people wise up fast) but might occur institutionally in the form of regulatory loopholes. Any lawyers on the blog?