EFF/KRF: Active management is always a zero sum game, before fees, expenses, and trading costs, regardless of market conditions. If there are active winners, they win at the expense of active losers. And active management is always a negative sum game after costs. This is an algebraic condition, not a hypothesis. We call it equilibrium accounting.
Moreover, our research on individual mutual funds says that it's impossible to identify true winners on a reliable basis, even if one ignores the costs that active funds impose on investors. Funds that seem to be winners, based on past returns, were probably lucky rather than smart. After costs, that is in terms of returns to investors, there is no game to play; there is no evidence of managers with enough information to cover costs, other than on a purely chance basis. And there is no evidence that this depends on market conditions. If you are interested, see our paper Mutual Fund Performance.
In short, passive management and passive investing always make sense.
Eugene Fama and Ken French are members of the Board of Directors of the general partner of, and provide consulting services to Dimensional Fund Advisors LP.