That was coined for investment capital that comes with a cost. E.g. (in its simplest) borrowing money to trade with, and then having to make regular payments to maintain your positions.
Assuming you have no pressing needs for your invested capital (e.g. most retail investors), the market cannot actually stay irrational longer than you can remain solvent.
Assuming you have no pressing needs for your invested capital (e.g. most retail investors), the market cannot actually stay irrational longer than you can remain solvent.