The corporate raider, who is angling to sell a 13 percent stake in Imclone Systems for more than $800 million, is piling up bets in biotech, according to data compiled by Bloomberg News.

Icahn and hedge funds he manages have accumulated stakes in at least 10 biotechs that comprise a fifth of their total publicly reported holdings, excluding shares of Icahn Enterprises LP. Icahn, 72, and the funds have about $1.3 billion invested in biotech, four times as much as two years ago, and increased those bets by $320 million in the last two months alone, Bloomberg writes.

“He’s trying to identify companies that he thinks major pharmaceutical companies’ managements might be attracted to, and he’s trying to stir up that attraction,” Tim Ghriskey, who helps manage $2 billion as chief investment officer at Solaris Asset Management, tells Bloomberg. “He’s simply priming the pump, or beating the drum, trying to stir up a potential sale.”

Since early August, Icahn has increased his investments in Biogen Idec and Amylin Pharmaceuticals by $320 million, raising his interest in the former to 6 percent and the latter to 7.3 percent. Amylin jumped 3.6 percent on September 12 after filings showed Icahn bought more shares. Biogen climbed 1.7 percent after reporting an increase in his position Aug. 11.

Icahn engineered his election as chairman of ImClone in October 2006, after doubling his holdings to the current level. Now he is pushing for a sale that may bring him and the hedge funds he manages at least $815 million in proceeds, assuming that a $70-a-share buyout materializes.

He recently indicated ImClone received a bid from an unnamed big drugmaker, and rejected a $60-a-share offer from Bristol-Myers, ImClone’s biggest shareholder and its partner for the cancer drug Erbitux. Bristol-Myers boosted its offer to $62 a share this week with plans to take its bid directly to ImClone shareholders through a tender offer. Icahn called the offer “absurd” and stressed the due diligence period for the $70-a-share offer from the mystery suitor ends on Sunday.

“He’s like a bulldog: He gets his teeth into something and doesn’t let go,” Samuel Hayes, professor emeritus of investment banking at Harvard Business School tells Bloomberg. “Managements fear him.”

Icahn and the funds purchased and sold ImClone shares at varying prices over the past nine years, and it’s not clear how much they would profit from a $70-a-share buyout. His most recent purchase, of 641,000 shares, was at prices between $29.91 and $30.15, according to a filing with the SEC on Sept. 15, 2006.

Icahn’s investment in MedImmune “is a pretty good testament to his dealmaking ability,” Chris Cernich, an analyst for Proxy Governance, which has advised shareholders in businesses involved with Icahn, tells Bloomberg.

Icahn disclosed he bought 1.1 percent of MedImmune shares in February 2007 amid investor dissatisfaction and pressured d MedImmune to put itself up for sale two months later. In June 2007, AstraZeneca completed a $15.2 billion buyout, an 86 percent increase in value from the day Icahn reported his stake (back story).

Icahn, an avid chess player and philosophy graduate from Princeton University, forged his reputation for aggressive investing in the 1980s, acquiring Trans World Airlines, then seeking to profit from Texaco bankruptcy. During the 1990s, he made $893 million trying to break up RJR Nabisco Holdings.

This year Icahn pushed Motorola to include two of his associates on its board and to split off its mobile-phone business into a separate entity. He was stymied in attempts to nudge Yahoo! into a sale to Microsoft, and he gave up efforts to oust Yahoo’s chief executive officer, Jerry Yang, in exchange for seats on the board. The two tech companies led Icahn’s hedge funds to losses of $773 million, or 9.1 percent, in the second quarter.

In his biotech investments, Icahn is betting on quick sales for easy profits, according to Cernich at Proxy Governance. “I’ve never heard his name in terms of a long-term buy and hold,” Cernich says. “He’s always agitating for a sale.”

Icahn’s biotech strategy hasn’t always proved successful. Last year, he bought into Biogen, the biggest maker of multiple sclerosis med, later tripling his stake to about 3 percent and proposed buying Biogen for $23 billion. That prompted the biotech to put itself up for sale, but when no official offers appeared, the for sale sign was pulled up and about $5 billion in market cap was wiped out that day. Icahn failed in June to persuade Biogen shareholders to elect his slate of directors to the company’s board, although he raised his stake to 6 percent as of August 11 (back story here and here).

“Shareholders know that for good or bad, Icahn gets in there and makes a difference,” Jake Dollarhide, chief executive officer of Longbow Asset Management, tells Bloomberg. “As an investor, I see Icahn’s presence as a bonus. Not everyone feels that way.”

Bristol-Myers is now about to find out exactly how tough a dealmaker Icahn can be. When Icahn announced the competing $70- a-share bid on Sept. 10, he said the potential buyer would have two weeks to probe ImClone’s records. He also said he hadn’t decided whether $70 was enough.

Whether a formal competing offer appears or not, Bristol-Myers may soon have to decide how long it can stand to face down Icahn. “You never know when Carl’s done,” Mark Stevens, the author of “King Icahn: The Biography of a Renegade Capitalist,” tells Bloomberg. “His clock and your clock are different. You should never think he’s walked away from you, because he probably hasn’t.”

Source: Bloomberg News