Billionaire Warren Buffett denies interest in acquiring another train company, dampening hopes of a CSX-BNSF merger. CSX shares fall 5% following his announcement. Buffett met with CSX CEO to discuss cooperation, not acquisition. CSX and BNSF announced coast-to-coast services, hinting at potential collaboration. Activist investors urge CSX to explore merger options.

Read more at Yahoo Finance: Buffett shoots down talk of Berkshire railroad merger, CSX shares slide