Business Live: Tesla shares plunge - BBC News
Traders sell stock after the electric car maker's Model S is rated 'acceptable' in a key test.
US stocks are still trading down, but why?

Chris Zaccarelli, chief investment officer at Cornerstone Financial Partners, says: "It's the lull before earnings. There's not as much enthusiasm for buying.

"Investors don't think companies will surprise as positively as they did in the first quarter."

Jan Dehn, fund manager at Ashmore, said investors may be spooked for other reasons.

"One is the Middle East and the Qatar-Saudi situation and even the oil market doesn't know how to handle that one," he said. "The second is North Korea, which is classic geopolitical risk, and finally, and probably most importantly, there has been the recent hawkish tilt from the major central banks and it seems to be coordinated."