After Shearson acquired its stake, members of senior management from both firms met to discuss a possible buyout.
The shares shot up by 16.5 pence, to 115, on London's stock exchange on news of the possible buyout.
American approached Pan Am about a possible buyout, industry sources said, and another bidder may also be interested.
"We don't give any credence to a possible buyout, so we would not adjust earnings or expectations for the company."
It said today that it was in discussions with Ashanti about a possible buyout.
Cummins suspended trading in its stock on Wednesday amid speculation of a possible buyout.
The shares were buoyed by speculation of a possible leveraged buyout or takeover.
It said the group had already begun talks with an unidentified investment banking firm about a possible leveraged buyout of the company.
Even so, rumors occasionally arise about a possible buyout.
Northwest Airlines' owner said a shareholder group had approached the company about a possible buyout.