Union Pacific , the largest U.S. railroad operator, said on Thursday it is in advanced talks with rival Norfolk Southern , signaling that a deal to form a $200 billion coast-to-coast rail company could be close - and potentially trigger further consolidation among remaining freight rail giants.

The combination of two large rail companies would create the first coast-to-coast network, but the deal could reduce competition.

Union Pacific and Norfolk Southern are nearing a $200 billion merger that could reshape U.S. freight transport, raising hopes for efficiency and concerns over competition.