In 2018, the average investor trailed the S&P 500 by 5.04%, according to the DALBAR QAIB study (1).
S&P 500 index = -4.38%
Average investor = -9.42%
Why? Don't ask your brain, ask your intuition.
Having a conversation with your colleagues...
"I am sure that a recession is coming, how can the market maintain this growth?"
"I totally agree, I just moved my portfolio to 70% bonds."
"That is a good idea."
Then you go home and trade your 401(k) from 70/30 equity to fixed income to 30/70.
What went wrong?