Canadian Pacific says it can give Norfolk Southern shareholders a premium approaching 60 percent with its cash-and-stock offer to combine the two North American railroad operators.

Canadian Pacific says it can give Norfolk Southern shareholders a premium approaching 60 percent with its cash-and-stock offer to combine the two North American railroad operators.

Norfolk Southern said late Tuesday that it received an unsolicited, low-premium offer of $46.72 in cash and a portion of Canadian Pacific shares for each of its shares. The deal value adds up to more than $28 billion, based on Tuesday closing prices, but Norfolk Southern noted that the total per-share price of $94.95 only amounts to a premium of less than 10 percent.

Canadian Pacific says Norfolk Southern Corp. shareholders need to consider the value of the new, combined company's stock when the deal closes in late 2017.

Norfolk Southern's stock and U.S.-traded shares of Canadian Pacific are both climbing in pre-market trading.