* Second time Icahn has taken a position in Talisman
* Doubts on whether activist investor can speed change
* Share fall 1 percent in afternoon trading (Updates shares and adds background.)
By Euan Rocha and Scott Haggett
TORONTO/CALGARY, Oct 8 (Reuters) - Talisman Energy Inc shares fell on Tuesday as investors raised doubts that activist investor Carl Icahn would be able to force dramatic changes on the struggling Canadian oil producer.
Icahn disclosed a 6 percent stake in Talisman late on Monday, making him its second-largest shareholder, according to Reuters data. It is the second time Icahn has taken a position in Talisman. He acquired 4.8 million shares in 2007, when the company was facing pressure to boost its share price.
Talisman shares have risen some 11 percent since the start of the month, as rumors swirled that an activist investor was building a position in the company. In the 12 months prior, the stock sagged 10 percent, despite a restructuring and asset sale program under a new management, as profits remained weak and its North Sea operations faltered.
"As a long-suffering shareholder, we are happy to see some price realization right now, but we are wary as the stock has already moved quite a bit in the last couple of weeks given the speculation around activist involvement," said Ryan Bushell a portfolio manager at Leon Frazer, which owns about 1.55 million Talisman shares, according to Thomson Reuters data.
"For the long term, whether this will result in taking the company where it needs to go - that for me is still very much in question."
The shares were down 1 percent afternoon trading on the Toronto Stock Exchange.
Icahn, 77, said in a filing with the U.S. Securities and Exchange Commission he intended to talk with Talisman's management to discuss strategic alternatives for the company, including asset sales or restructuring. He might also seek a board seat, according to the filing.
Many analysts noted that Talisman has already been working on a restructuring and asset sales process for months.
"Although the presence of Icahn's beneficial interest may excite some investors, we remain cautious on the story going forward, particularly given that management is currently in the midst of a portfolio restructuring initiative," JPMorgan analyst Katherine Minyard said in a note to clients.
"Moreover, we believe that any positive investor sentiment may be tempered over the long run as long as Talisman retains a somewhat scattered and unfocused portfolio."
Talisman was the Canadian unit of BP Plc before being spun off in 1992. Under the leadership of Jim Buckee, the company embarked on an acquisition spree, including a controversial stake in a Sudan oilfield that made Talisman the target of human-rights protesters who said oil revenues were aiding the government during a brutal civil war.
Buckee sold the Sudan assets in 2003. By the time he retired in 2007, Talisman was Canada's No.3 oil producer. But even then, it faced pressure to split up its global operations, a step both Buckee and Manzoni, his successor, rejected.
Hal Kvisle, who took over as Talisman chief executive in September 2012 following the abrupt departure of John Manzoni, is refocusing the company's sprawling global presence to concentrate operations in North and South America and Southeast Asia. He is also restructuring production away from low-value natural gas.
The company is looking to raise as much as $3 billion from asset sales this year. Talisman is looking to sell lands in the North Duvernay shale-gas region of Alberta and parts of its holdings in the Montney field, which straddles Alberta and northeastern British Columbia.
It is also looking to sell its 12.15 percent stake in the Ocensa pipeline, which carries 650,000 barrel of oil per day from Colombia's interior to an oil port on the country's Atlantic coast. Sources have also told Reuters the company is exploring the sale of its shale assets in the Eagle Ford basin in south Texas.
Talisman completed the sale of a 49 percent stake in its North Sea operations to Sinopec for $1.5 billion in December.
BMO analyst Randy Ollenberger sees Icahn's involvement as a potential catalyst for Talisman's stock price.
"However, the sale of all or part of the company will clearly take time and there are no guarantees the company is able to achieve prices that will meet the market's expectations," Ollenberger said in a note to clients. (Reporting by Euan Rocha and Scott Haggett; Editing by John Wallace and Andre Grenon)