Stocks look set to extend losses as the U.S. State Department issued a worldwide travel warning to Americans. There is concern that terror groups plan more attacks in the wake of massacres in Paris and Mali. The alert doesn't mention any specific destinations. Meanwhile, Russia says one of its jets was shot down near the Syria-Turkey border. High profile activists investors are in the headlines this morning. Carl Icahn has taken a 7% stake in Xerox (XRX). He says that he would have discussions with Xerox's Board of Directors about improving operational performance and pursuing strategic alternatives as well as attaining board representation. Bill Ackman is boosting his stake in Valeant (VRX) to just under 10%. The embattled drugmaker that's seen its shares fall 60% over the past 3 months amid scrutiny into its business practices and drug pricing strategies.