Like vultures sensing wounded prey, they are circling two of America's best-known and badly troubled companies. At an age when most are deeply into retirement, the billionaire financiers Kirk Kerkorian and Carl Icahn - two of the most notorious corporate raiders during the hey-day of hostile takeovers on Wall Street - are back in the headlines.
Mr Kerkorian, 86, disclosed last Wednesday that he had made an offer for 9% of General Motors, the world's largest carmaker, which is facing a worsening financial crisis. Mr Icahn, a relatively sprightly 69, is simultaneously engaged in an increasingly ferocious attack on the management at Blockbuster, the video rental chain.
Both men cemented their reputations in the 1980s when their combative investment style made them among the most feared men in corporate America, launching hostile takeovers, forcing break-ups and overthrowing boards.
In his own recent marketing materials to raise money for a planned hedge fund, Mr Icahn boasts of his spine-chilling effect on chief executives. "Mr Icahn has a reputation as a formidable adversary," it reads. "Companies take him seriously and often take actions to enhance shareholder value when they know Mr Icahn has a position in their securities."
Their pursuit of broken or undervalued companies also made them enormously wealthy. According to the Forbes rich list, Mr Kerkorian is worth $8.9bn (£4.7bn), making him the 41st richest man in the world. Mr Icahn is a few places below, at number 49, with wealth of $7.8bn.
The power that the two billionaires wield has clearly not diminished with age.
Last week's disclosure that Mr Kerkorian was taking a sizeable stake in GM sent shares in the company 18% higher to $32.80. In a statement, his investment group Tracinda said it had bought 22m shares, around 3.9%, in the past few weeks and was offering $868m for another 28m.
The financier's lawyer, Terry Christensen, said the investment was intended to be a passive one. Mr Kerkorian, he added, did not intend to lift his stake further at present and had confidence in the carmaker's management, led by Rick Wagoner, the chief executive.
"He's not really trying to judge management," Mr Christensen told the New York Times. "He's trying to judge the assets of the company, the ability of the company to right itself and get going strong again."
Falling SUV sales
GM's woes have been widely reported. The company reported a $1.1bn loss in the first quarter, its worst performance in a decade. It faces dwindling market share in the US, a worsening product mix as sales of sport utility vehicles plummet, rising raw material costs and the soaring cost of providing healthcare for its American workers.
Wall Street, dismissing the comments of Mr Kerkorian's lawyer, is anticipating further action.
Among the many suggestions: he could attempt to pressure the company into selling its profitable finance arm, force his way on to the board, increase pressure to cut costs, or strong-arm the firm into handing some of its cash pile back to shareholders. He could also be just enough of a thorn in the company's side that it buys his shares back - delivering him a quick profit.
Mr Kerkorian, born in Fresno, California, to Armenian immigrants, does have a history of highly active investing.
A boxer and then a civilian pilot for the Royal Air Force during the second world war, he made his first million in the airline business when he started out flying charters to Las Vegas after the war.
He built some of the largest hotel casinos in Las Vegas, including the MGM Grand. He sold his empire there once but returned to build the MGM Mirage business, in which he still has a controlling interest. The company earlier this year bought a rival, Mandalay, for $8bn.
He bought and sold the MGM film studio three times. In the most recent transaction, he sold the business to a group of investors led by Sony for $5bn.
Mr Kerkorian has already had a brush with the auto industry. In the mid-1990s he launched a failed takeover bid for Chrysler that left him with a large stake in the company. When it then merged with Daimler he made about $3.5bn.
Earlier this year he lost a lawsuit claiming that Daimler's deal with Chrysler had robbed shareholders of billions of dollars more by casting it as a merger when it was really a takeover.
At Blockbuster there is no pretence at civility. Mr Icahn has attacked the firm's chief executive, John Antioco, over the size of his compensation and railed against his strategy to find new revenue streams to replace the diminishing video rental market.
Mr Icahn, who owns almost 10% of the company, has proposed a slate of his own directors to be voted on at the firm's annual meeting. He hijacked an analyst conference call to discuss Blockbuster's first-quarter results and grilled Mr Antioco over his bonuses. He wants Blockbuster to focus on its core business, pay out huge dividends and to put itself up for sale.
Poker winnings
Mr Antioco said last week there was no justification for Mr Icahn's actions. "Mr Icahn doesn't know our business," he said. Blockbuster reported a first-quarter loss of $57.5m, in large part due to higher marketing costs. The company is attempting to build an online delivery service and recently scrapped late fees.
Mr Icahn, who graduated from Princeton University with a philosophy degree, is said to have arrived on Wall Street with just $4,000 in poker winnings that he parlayed into his massive fortune.
He is best known for taking over TWA, the airline, in the mid-1980s, although his skills as a manager are less certain than his abilities as an investor. The airline went bankrupt under his aegis in the early 1990s. He also made tilts at US Steel and Texaco. In another famous assault, he tried to gain control of RJR Nabisco and failed - but still pocketed $893m when the company, under pressure, spun-off its tobacco arm and sought a deal with Philip Morris.
Mr Icahn has been active again of late and is living up to his reputation for being irascible.
While the drug company Mylan Laboratories was pursuing an unpopular takeover deal of King Pharmaceuticals, he took advantage of the depressed Mylan share price to snap up 10% and then successfully campaigned against the deal.
The US energy firm Kerr-McGee thwarted a challenge from Mr Icahn only after promising last month to carry out a series of disposals and buy back $4bn of its own shares. The announcement led to an immediate jump in the share price and a $57m profit for Mr Icahn.
He acquired a stake in the scandal-hit financial services group Skandia of Sweden at the end of last year and also owns a big chunk of Eastman Kodak, the struggling photographic firm.
There had been some speculation that Mr Kerkorian was finally looking to tidy his portfolio ahead of retirement but the GM investment says otherwise. Mr Icahn clearly has no such plans. He is in the process of raising $3bn for a hedge fund.
With the fortunes they have already amassed, it seems reasonable to ask why both men are still happily creating trouble. Mark Stevens, author of King Icahn, took a stab at an explanation of Mr Icahn's motivation at least to a Fort Worth newspaper, close to Blockbuster's home town of Dallas. "His motive is always the same, ultimately; to: A, make money, and B, demonstrate his intellectual and macho superiority to the people he's dealing with. It comes out of pride."
