Wall Street sheds gains as oil slide weighs

Wall Street retreated sharply in volatile trading on Thursday as a slide in oil prices undermined gains from the European Central Bank's move to cut rates and expand its stimulus program. The ECB pushed deposit rate deeper into negative territory and increased its asset-buying program to 80 billion euros a month from 60 billion euros in an effort to boost growth in the region. "Europe continues to be stimulative...(but) there's only so much this can continue to help the markets," said Philip Bla