Historically, the S&P 500 has come back from every one of its downturns to eventually make investors whole again.

The long-term impact of the new US tariffs implemented by President Donald Trump may be uncertain, but the short-term effects have been obvious -- stock prices in the leading US markets are crumbling.

Fear is running high amid the worst stock sell-off in years. It's important for investors not to panic as they watch their portfolios take a hit.