He will remain chairman of the board during his treatment. Pursuant to a long-established plan for such situations, John Koraleski, executive vice president-marketing and sales, will serve as acting president and CEO during Young's absence.

Steven Rogel, Union Pacific's lead independent director, said: "The board has a great deal of confidence in Jack, Rob Knight our CFO, Lance Fritz our head of operations and the entire management team. We are confident that our company will continue to provide great service to our customers while meeting the financial and safety objectives we have set for ourselves and our shareholders expect."