Union Pacific is reportedly considering acquiring a rival railroad, sending shares of CSX and Norfolk Southern higher.

Union Pacific is in talks to merge with Norfolk Southern, according to The Wall Street Journal, in a deal that would shake up the railroad business in America.The Journal cited people familiar with the matter.

CSX has a $62.5 billion market capitalization, compared to $58.7 billion for Norfolk Southern. Union Pacific is the largest of the three S&P 500 railroad stocks, with a $138.1 billion market cap. BofA also cited CSX's internal improvements in the upgrade, according to The Fly investment site.