We always say "probability", in other words "odds of winning" which indirectly means there are chances that it may not happen at that time. Hence timing is critical for success in stock market. No one can time the markets but as long as we can read the signs we can protect our capital as well as gains. In short, having a plan always works not just for stock market but also in life.
What do we do with...
401K Investments: If you are already invested then wait for SELL signal. If you missed the rally or prematurely got out of market then wait for next BUY signal.
ETF/Stocks Investments: You can continue to invest but be careful and use stop limits no matter what.
Capital preservation must be our TOP priority... be alert and cautious.