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Big-name investors like David Einhorn, Bill Ackman and Carl Icahn took the stage to offer a slew of recommendations at the annual Sohn investment conference in New York Wednesday. But the biggest market move came from a plug for an education company from an Indiana University student who won the right to present his idea in a stock-picking contest sponsored by the Sohn Foundation.

A confident Sunjay Gorawara recommended Bridgepoint Education (BPI), whose shares jumped 13%, to 23, after he said the company, which offers online courses to adults, looked inexpensive trading at under three times pretax cash flow and with 30% of its market value in cash.

Einhorn, who heads Greenlight Capital, caused the biggest stir when he said Microsoft (MSFT) is a buy but that CEO Steve Ballmer must go. "His continued presence is the biggest overhang on Microsoft stock," Einhorn said. He noted that Microsoft now trades for just seven times forward earnings, excluding its big net-cash position.

Ballmer, Einhorn said, is a poor allocator of capital, pointing to the recent $8.5 billion deal to buy Skype, and the $45 billion offer for Yahoo! (YHOO) in 2008 at about double Yahoo's current price; fortunately for Microsoft, it was rejected by Yahoo. Microsoft shares rose 48 cents Thursday, to 24.67, in response to Einhorn's call.

Einhorn also recommended Delta Lloyd (DL.Netherlands), a Dutch insurer whose shares, at around 15 euros ($21.43), trade for 70% of book value, six times earnings and carry a 6% dividend yield. Einhorn ended his presentation with a "Go, Mets!" cheer, an exclamation whose significance became apparent the next day with news that he is close to a deal to buy a sizable minority stake in the New York baseball team for $200 million.

Pershing Square's Ackman talked up Family Dollar Stores (FDO), arguing that the retailer to lower-income customers should be able to lift margins, and could be bought by rival Dollar General or private-equity buyers at a big premium. Family Dollar stock, which rose $2, to 55, trades for about 15 times fiscal 2012 profit of $3.65.

Icahn plugged a name with "great management: me." That is Icahn Enterprises (IEP), a limited partnership whose shares fetch 42. Icahn controls 92% of Icahn Enterprises, which has almost $1 billion in cash, a $2.8 billion stake in Icahn's hedge fund, a 76% interest in auto-parts supplier Federal-Mogul (FDML), as well as casino, textile and other assets, offset by $3 billion of debt. The billionaire said that his investment vehicle is "very undervalued" in light of its assets and its track record. "Why I don't get a premium and Warren does, it bothers me a little," Icahn said, referring to Warren Buffett's Berkshire Hathaway (BRKA) . "Maybe it's because he's a little older...You're getting me for a negative value." Icahn is 75, and Buffett, 80.

Conference-goers would have done well to heed the Tiffany (TIF) recommendation of Peter May, a principal at Trian Fund Management and a Tiffany director. The jewelry retailer posted strong results the next day, and its shares rose $6, to 76. May, who said his presentation was based on public information, argued that the company could have "substantial earnings growth" from new stores, higher sales at existing ones, and product extensions like handbags. He said the stock could hit 100.

Former mutual-fund manager Michael Price of MFP Investors had good words for Goldman Sachs Group (GS) and Citigroup (C), saying that the depressed Goldman could be worth $100 more than its current share price of 136, based on a sum-of-the-parts analysis. "It has a tremendous business with honest people, and a history of doing well," Price said.

Dinakar Singh of TPG-Axon Capital recommended Orkla (ORK.Norway), a conglomerate whose stock, at around 49 Norwegian kroner ($9), could be worth more than 70 NOK in a break-up. He also likes Sprint Nextel (S), and says the No. 3 U.S. wireless provider is solving its operational problems, and could benefit by picking up attractive assets that may have to be sold by AT&T to gain clearance for its T-Mobile merger.

Noted short-seller Jim Chanos of Kynikos Associates said wind and solar stocks are vulnerable because these much-vaunted energy sources aren't competitive now, with natural-gas prices so low. "That has put an economic arrow into the heart of these industries," he said. He's bearish on Vestas Wind Systems (VWDRY), a leading maker of wind turbines, and First Solar (FSLR), a maker of solar panels.

Mark Hart, of little-known Texas firm Corriente Advisors, outlined a bearish investment case on China, saying that "signs of a bubble are everywhere." He argued that Chinese banks likely are sitting with a rising amount of bad loans contrary to official statistics and that reported Chinese inflation is understated. He challenged the conventional view that the Chinese currency can only go higher. Hart said that the yuan could fall, and that a Chinese economic and financial crisis could dwarf the Asian financial mess of 1997. Yuan puts bearish bets on the currency are very inexpensive now, thanks to near-certainty in the markets that it will appreciate relative to the dollar.

Steve Eisman of FrontPoint Partners recommended property- and casualty-insurance stocks, saying that industry pricing is starting to turn higher, and that many stocks trade at or below book value. Jeff Aronson of Centerbridge Partners likes CIT (CIT), the commercial lender that emerged from bankruptcy in 2009. He pegs "intrinsic value" near 59, versus its recent share price of 43. He believes the company should benefit from lower funding costs, and could be a takeover target at around 65.

Einhorn: Jonathan Fickies / Bloomberg News; Chanos: Jin Lee / Bloomberg News; Price: Ramin Talaie / Bloomberg New