if you do that, the risk is that you miss out on buying at low share prices during the slump, which will be the lots that show the highest return when the market heads back toward normal.

The periods of fastest gains are usually immediately following a downturn, so selling your holdings when you hear bad news about the stock market going down, is exactly the wrong thing to do.

If you believe that The Trump administration policies represent a foundational destabilization of the American economy, which is a reasonable take, you might make the choice to diversify into more international funds.