Activist investors return

Activist investors are back. A whole new generation of cage-rattlers are taking on some of the world's biggest corporations – and some of the original activists of the 1980s have returned to the fray with a bang. As Carl Icahn buys big in Apple and Dell, Dan Loeb counts his Yahoo profits, and they both tussle with Bill Ackman over Herbalife, here are ten of the most successful activist investors and their most famously profitable deals.

Big win: RJR Nabisco

Share gain: 83% (Reuters data)

Icahn hit headlines recently over high-profile stakes in Dell, Apple and Herbalife, but this is far from his first act of shareholder activism. His battle with the board of Oreos maker RJR Nabisco was notoriously long and bloody, and took most of the 1990s to resolve. Icahn's main aim was to separate the tobacco operation, which was at that point becoming increasingly vulnerable to lawsuits, from its food unit. When he eventually achieved his aim, he had made $1.3 billion in total, and Philip Morris paid $55 per share for Nabisco (without its tobacco operations), compared to the average $30 per share he bought it at (according to contemporaneous reports by the New York Times). Icahn's tenure at TWA, which ended in the august airline's bankruptcy, was notoriously less successful.

(Read more: Carl Icahn is 77. Big deal)

Big win: Gulf Oil

Share gain: 74% (Reuters data)

One of the original activist investors, Pickens amassed a hefty fortune through oil, then moved into another league of wealth through forcing change at Gulf Oil, Unocal, Pioneer and others via his Mesa investment fund in the 1980s. The billionaire made his name as a corporate raider, making $404 million for shareholders in his battle with Gulf Oil, according to his autobiography "Boone Pickens: The Luckiest Guy in the World". He didn't succeed in gaining control of the company, but its eventual merger with Chevron at $80 per share was a hefty premium on the $46 per share it traded at before his plan emerged.

Big win: Yahoo!

Share gain: 129% (Reuters data)

The board of Yahoo! didn't really know what hit them in September 2011 when Loeb's Third Point fund announced in an SEC filing it had bought a 5.2 percent stake, at $12.72 per share. Within the year, almost all of the board had exited, and Google executive Marissa Mayer had been brought in as chief executive. By then the share price had already risen to $15.40. Loeb quit the board and sold part of Third Point's investment in July at $29.11 per share, a 129 percent rise on its initial purchase price, making a profitof $655 million.

Big win: Canadian Pacific Railway

Share gain: 112.38% (Reuters data)

The head of $12 billion hedge fund Pershing Square Capital, currently embroiled in a feud with Icahn and Loeb over Herbalife, made his name through a six-year battle with bond insurer MBIA. His short position on the company was eventually proved right when it collapsed during the 2008 financial crisis, making Ackman and his investors more than $1 billion, according to Confidence Game, Christine S.Richard's account of the deal.

A more immediate result came when he invested in Canadian Pacific Railway in October 2011, forcing most of the board out by the following July, and engineering a 112.38 percent rise in the share price by June this year, when Pershing sold down 25 percent of its stake.

Big win: Snapple

Share gain: N/A ($1.15 billion profit according to Forbes)

Peltz, with partners Peter May and Ed Garden, has waged war on household names from Heinz to Pepsi –which he is currently lobbying to buy Mondelez and spin off its North American beverage business. He courted Snapple for years after his Triarc fund paid $71.8 million for a 23.1 percent stake in the business, then controlled by Quaker, before finally securing control in 1997 for $300 million. The price,just over half the drink's annual sales, was considered bargain basement at the time. After a turnaround plan, it was sold to Cadbury Schweppes in 2000 for $910 million in cash, with about $420 million in debt assumed by Cadbury and$120 million in employee options.

Big win: CNet

Share gain: 45%

Rosenstein's Jana Partners led a consortium trying to force change at internet company CNet in 2008 (see SEC filing on purchase). They didn't quite succeed in forcing the changes they wanted, but they did make a tidy profit when CBS struck a deal to acquire CNet for $11.50 within months of Jana buying a stake. Since then, Rosenstein has aggressively pursued the break-up of McGraw-Hill and the sale of Coventry Health Care.

Big win: Shorting Lehman Brothers

Shorting Lehman Brothers in July 2007 seems like a stroke of genius in retrospect. At the time, Einhorn's public announcement that he was shorting the stock – and his prolonged battle with management over its problems with leverage before its eventual collapse – was controversial enough to merit an SEC investigation.There are still some who credit the Greenlight Capital founder's open criticism with bringing about the venerable bank's demise. He has also engaged in high-profile battles with Allied Capital and made a move on a minority stake in the New York Mets. A talented poker player who once came 16^th in the World Series of Poker, Einhorn was fined by the U.K. authorities for insider trading in Punch Taverns shares, a charge he denied strongly.

Big win: Metso

Share gain: 96% (Reuters)

The founders of Cevian Capital, Europe's largest activist fund, are generally happy to stay under the radar and prefer a collaborative approach, rather than the aggression typical of some other activist investors. Their recent investment in German steelmaker ThyssenKrupp, which is struggling after attempts to expand in the U.S. and may need to raise capital later this year, is a case in point. In the case of Finnish engineering company Metso, however their campaign for change has gone on for eight years, culminating earlier this year in the demerger of its paper, pulp and power business. They have been endorsed by no less than Carl Icahn,who has bought into several of their funds.

Big win: Waste Management Inc

Share gain: 60% (Reuters)

Whitworth learned activist investing from working for T. Boone Pickens, before starting up Relational Investors. Since then, he has built a reputation as an expert in corporate governance. He's currently serving as interim chairman at troubled computer company Hewlett-Packard, and handling the fallout from its disastrous purchase of Autonomy. At Waste Management, he took over as chairman in 1999 when it was dealing with the fallout from poor accounting practices and a messy merger. By the time he stepped down in 2004, the company's fortunes, board and account books had had a thorough overhaul.

Big win: Suez

Share gain: nearly 100% (according to the Financial Times)

An alumnus of England's prestigious Eton College boarding school, Knight (pictured center) is renowned for his politeness even to those he's doing battle with – including the boards of Shell, HSBC and, more recently, UBS. In the case of Shell, his lobbying was instrumental in the oil giant's amalgamation of its Dutch and British arms, according to Business Week. Suez, the French conglomerate, was one of his first high-profile campaigns. While the board didn't enact all of his six proposals, he still managed to put enough pressure on it that his fund Knight Vinke's stake doubled in value.