X XCLX - Xcel Energy XCWZ - Union Pacific Railroad XFEZ - Florida East Coast Railway XNWZ - Norfolk Southern Railway XOMX - Exxon-Mobil Corporation XRFZ - CSX Transportation XSCZ - CSX Transportation XSLZ - Soo Line Railroad XTRX - XTRA, Inc.; First Union Rail XTTX - Trailer Train Company