Union Pacific Corp. is exploring an acquisition of Norfolk Southern Corp., setting up what could rank as the largest railroad deal ever, according to people familiar with the matter.

Union Pacific Corp. is exploring an acquisition of Norfolk Southern Corp., the Wall Street Journal reported, setting up what could rank as the largest railroad deal ever. The talks are at an early stage and there’s no guarantee they will reach a deal, according to the report, which cited unidentified people familiar with the matter.