Market strategists see more pain ahead as a result of tariff-induced volatility. "We think it's too early to go bargain shopping," an investment chief wrote.

Specifically, the S&P 500 declined 19.8% over a three-month period between September and December 2018, but the index had recouped its losses and reached a new high by May 2019. That's because the market tends to overreact to good and bad news.