Oil prices have fallen 32% in less than two months and last week recorded their worst week since the financial crisis. Industrial metals from copper to aluminum are also taking a beating, Ramkumar notes.
The big picture: Commodity prices can provide a real-time indicator of activity, and "the current slide reflects slumping demand and bloated inventories."
Plus, "some investors worry the widespread selling of assets associated with risk also portends more pain ahead for stocks."