Tiffany Tanks on 'Disappointing' Holiday Sales, Stocks Slip on Oil

Falling oil prices were back to driving the markets lower at midday trading on Monday. Despite opening higher, stocks gave back their gains. Schlumberger (SLB) is falling after the world's largest oilfield services provider was downgraded at Goldman Sachs. Other energy stocks like Transocean (RIG) and Nabors (NBR) are also contributing to pushing the markets lower. Luxury jeweler Tiffany (TIF) is tanking after cutting its guidance for the full year following a 'disappointing' holiday season. There are some bright spots in the market. Bristol-Myers Squibb (BMY) is climbing after saying its cancer treatment drug showed better overall survival rates compared to a form of chemotherapy for lung cancer patients.