Stocks may be coming off their best day in two weeks, but Ned Davis Research's Ed Clissold sees near-term trouble ahead.

While midterm election years are typically associated with third quarter pullbacks, his latest indicators suggest the ultimate catalyst could come from abroad. According to Clissold, international issues are just as likely to drive corrections in midterm years as domestic issues. In a world where emerging markets are struggling and trade war fallout is lurking, this year may be even more vulnerable.