The S&P 500 ended with slight gains, coming back from Tuesday's massive losses. An attack outside of British Parliament kept markets on edge for much of the day. Police said they were treating the incident as an act of terrorism. Nike (NKE) - Get Report was a major weight on the Dow Jones Industrial Average following weaker-than-expected guidance. Worldwide futures orders, an indicator of sales over coming quarters, fell 4% and the company anticipates current quarter sales growth in the mid-single digits. FedEx (FDX) - Get Report shipped fewer packages over the holiday season than it had anticipated. The delivery company said it had provided capacity over its recent quarter that went unused. Snap (SNAP) - Get Report rose after receiving its second buy rating from an analyst firm yesterday. The disappearing message app was started at buy at Drexel Hamilton.