STB Halts Union Pacific-Norfolk Southern Merger Review, Requests More Data

The Surface Transportation Board (STB) suspended its review of the proposed merger between Union Pacific Corp. (NYSE:UNP) and Norfolk Southern Corp. (NYSE:NSC) on May 29, 2026, citing the need for additional competitive-impact data. The decision pauses a process that would have combined two of the largest U.S. freight railroads into a network spanning 32,000 miles. Union Pacific and Norfolk Southern announced the cash-and-stock deal in March 2026, aiming to create a dominant transcontinental carrier. The STB, which has not approved a major railroad merger since the 1990s, must weigh whether the combination would enhance or harm competition. The agency said the hold will remain until the companies submit detailed traffic density studies and revised service assurance plans. Analysts had anticipated heightened scrutiny given potential overlap in the eastern U.S. and grain-shipping corridors. Both Union Pacific and Norfolk Southern shares dipped in pre-market trading following the announcement.