NEW YORK (Standard & Poor's) Aug. 5, 2003--Standard & Poor's Ratings Services said today that it affirmed its ratings on Union Pacific Corp. (BBB/Positive/A-2) following the company's announcement that its board of directors approved the sale of its less-than-truckload (LTL) trucking subsidiary, Overnite Corp., through an initial public offering. The sale of Overnite would be a positive development because it would allow Union Pacific to concentrate on its core rail operations and could also generate a meaningful level of cash proceeds. However, at this time, the amount of likely proceeds is uncertain and the company has not elaborated on how it would use the proceeds. If the public offering is successful and Union Pacific uses proceeds along with expected strong