** Railroad operator's shares up 9.8 pct at $88.62; Canadian Pacific Railway's U.S.-listed shares up 6.31 pct at $142.28 in extended trading
** Canadian Pacific exploring acquisition of peer Norfolk Southern, a person familiar with the matter told Reuters on Monday
** The two rail companies have held preliminary merger talks, but there is no certainty that negotiations will advance, the person said
** Norfolk Southern declined to comment and CP Rail said in a release that it has "no material news pending at this time"
** More than 8.6 mln shares traded, 4.2 times their 25-day moving avg
** Up to Friday's close, stock had fallen nearly 28 pct this year