The US economy may be inching closer to the cliff edge given these 4 troubling signs, Larry Summers says

• Ex-Treasury chief Larry Summers thinks the economy is edging closer to a "Wile E. Coyote" fall off a cliff. 
• Rising inventories and dwindling savings are among key factors threatening the US economy's current robustness, he said. 
• "People may be reading a bit too much into the moment in terms of economic strength," he warned. 

Former Treasury Secretary Larry Summers highlighted four troubling signs of potential risks to the US economy's current robustness.