The Market Can Stay Irrational Longer

This line is widely attributed to Keynes, though its precise origin is contested — it does not appear verbatim in his published writings. It is often associated with his observation in The General Theory (1936) that professional investment resembles a beauty contest where participants must predict not who is most beautiful, but who others will think is most beautiful. Keynes drew on his own experience managing the King's College Cambridge endowment, where he suffered significant early losses from attempting to time markets.