Standard&Poor's Ratings Services bases its corporate credit rating on Public Service Co. of Colorado (PSCO; BBB/Stable/--) on the consolidated credit profile of Xcel Energy Inc. (BBB/Stable/--), the parent company of PSCO, Northern States Power Co. (NSP-Minnesota; BBB/Stable/--), Northern States Power Wisconsin (NSP-Wisconsin; BBB+/Stable/--), and Southwestern Public Service Co. (SPS; BBB/Stable/--). The rating reflects the strength of the utilities' business profile ('5' on a scale of '1' to '10', with '10' being the weakest), which incorporates the generally supportive state regulation that governs each utility's rates, the relatively low-cost power supply and overall fuel diversity, and the broad geographic region encompassed by the combined service territories of Xcel Energy's subsidiaries. Xcel Energy has only a small amount of unregulated
