For many investors, the moves reflect the mixed economic data and weak global economic backdrop that’s confounded investors this year. But for some, there’s fear that a bigger selloff may be in store.

“All it takes is one shock to trigger another violent sell off, or worse… the end of the greatest debt-fueled cycle on record at a time when central banks are effectively out of ammunition,” said Luke Patterson, CEO and chief investment officer at Avidian Wealth Management, in a Tuesday report.