The S&P 500 is up 21.54% (Morningstar, intraday 11/8/2017) since the Trump rally began one year ago. While corporate earnings are up, price multiples have also expanded with growing optimism of policy reforms that could further improve earnings growth. This leaves many investors wondering if they should simply go to cash to lock in the gains.

For a long-term investor, someone who doesn’t plan to use the money for at least 5 years, this might not be a clever idea. To illustrate, let’s assume that we perceive an elevated risk of a 15% correction to get back in line with normal growth from where we were a year ago. From that level, we might expect 8% to 10% average annual growth. If we are correct, and the market goes down 15%, and then grows at 8% per year for 3 years, it would still be worth more than if it were left in cash.

To illustrate, a $100 investment that declines by 15% is worth $85. Then if it grows by 8% per year for 3 years (85 x 1.08^3), it would be worth $107.07. That implies cash would have to earn 2.3% per year to keep up, and that is not available in today’s low-interest rate market without material risk.

As a short-term tactical move, cash can serve as an effective hedge against a falling market, but only if an investor has the fortitude to use it and invest when fear is at its height.
Perhaps the greatest risk for a long-term investor is selling out, not taking advantage of a market correction, and then reinvesting when higher prices signal all clear. It happens all the time.