* U.S. crude wallowed at its lowest since 2003 and Brent crude fell to near 12-year lows. * The U.S. market has been roiled this year due to slumping oil prices and weak economic data out of China, the world’s second-largest economy and a key market for major U.S. companies. * The S&P 500 has fallen 8 percent so far this year, wiping off more than $1.4 trillion, while global markets have lost $4.2 trillion, according to Thomson Reuters data.