(Reuters) -Berkshire Hathaway is not in the market to buy a train company, CEO Warren Buffett said to CNBC on Monday.

The news comes weeks after reports on Berkshire-owned BNSF being in talks to acquire CSX Corp to create a transcontinental railroad.

Shares of CSX fell about 4.5% after the news.

Last week, CSX and BNSF announced a new coast-to-coast service.

U.S. railroad leader Union Pacific and Norfolk Southern last month announced a $85 billion merger proposal, fueling speculation that more mergers in the industry could follow.

BNSF and CSX did not immediately respond to Reuters requests for comment.