U.S. rail regulator pauses review of UP-Norfolk Southern merger, asking for more detail

The Surface Transportation Board (STB) has accepted Union Pacific’s and Norfolk Southern’s revised application for their proposed merger, but paused the formal merits review, according to the agency’s decision released May 28. While the STB said the filing meets the regulator’s narrow “completeness” threshold, it also said several aspects of the revised application are “unclear or underdeveloped,” requiring further supplementation before the board can evaluate whether the deal is in the public interest.

In the same decision, the STB placed the entire proceeding, including the environmental review, into abeyance and ordered the railroads to submit supplemental information by July 27, 2026. The agency said the purpose of the delay is to ensure the board and the public can fully evaluate the transaction rather than respond to complex issues before key information is developed.

The STB’s request for more information spans a broad set of topics central to how major railroad combinations are reviewed. The ordered supplemental materials include additional analysis on enhanced competition, access for 2-to-1 and 3-to-2 shippers, a diversion analysis for public benefits, and a service assurance plan. The board also asked for supplemental work on gateways and car supply issues involving TRRA, KCT, and TTX, market share projections, downstream merger impacts, passenger rail effects, and supporting workpapers.

STB documents also addressed how parties engage in the proceeding. The board denied a request by the applicants to waive the prohibition on ex parte (one-on-one, off-the-record) communications in railroad merger cases at this stage, saying a broad waiver could complicate record building. The agency said it could re-evaluate a potential waiver later if specific issues arise for which such communications would be valuable.

Union Pacific and Norfolk Southern said the STB’s action was an important step forward. In a joint statement accompanying the filing’s acceptance, Union Pacific CEO Jim Vena said the companies submitted a “comprehensive, data-driven application” and are prepared to show the facts behind the merger’s expected benefits. Norfolk Southern CEO Mark George said the additional detail in the amended application strengthened its analysis and set the stage for a “full and transparent review.”

Market attention is focused on how this phase affects timing. A Reuters report said the STB paused the review while seeking more information and noted that the railroads expect completion in mid-2027, compared with an earlier April 2027 expectation. The STB’s own decision emphasized that acceptance of a revised filing as “complete” is not an approval of the merger, and it did not establish firm dates for subsequent participation and filings until the supplemental package is reviewed.

The outcome matters for the broader U.S. freight-rail landscape because a successful merger would effectively create a coast-to-coast single-line option spanning the two networks. That is also why the STB’s supplemental requests are tightly connected to competition and service outcomes, including how shipper access would work for shippers that currently have limited routing options and how the combined system would manage expected traffic growth.

Even with acceptance of the revised application for consideration, the STB left multiple moving parts unresolved until July. The decision does not publicly disclose which specific portions of the railroads’ amended materials it considers deficient, beyond describing them as unclear or underdeveloped, nor does it provide a full schedule for later merits proceedings before supplemental information is filed and evaluated.