Influential hedge fund manager David Einhorn called on Microsoft's Chief Executive Steve Ballmer to step down, while famed short-seller Jim Chanos threw cold water on alternative energy companies during the annual Ira Sohn Investment Research Conference on Wednesday.

Ballmer, who succeeded co-founder Bill Gates in 2000, is stuck in the past and has become the biggest overhang on Microsoft's stock, said Einhorn, who rose to prominence for making a prescient call on Lehman Brothers' accounting troubles before the firm's collapse.

Following his comments, Microsoft Corp shares traded as high as $24.40 after-hours, 0.86 percent higher than the Wednesday closing of $24.19. Einhorn's Greenlight Capital holds about 9 million Microsoft shares, or 0.11 percent of the company's outstanding shares, according to Thomson Reuters data.

In another high moment of the conference, Jim Chanos recommended investors short solar and wind energy companies such as First Solar Inc and Vestas Wind Systems.

In a presentation that prompted rare laughter from the audience, he recognized his investment idea would disappoint greenies and those in power.

Below is a compilation of the main investment ideas floated at the conference:

JIM CHANOS, KYNIKOS ASSOCIATES

IDEA: short wind turbine manufacturer Vestas and solar company First Solar.

Chanos laid out why he thinks alternative energy is no panacea and will not create the jobs the Obama administration has predicted -- a contrarian idea to many investors.

Some analysts are skeptical that Vestas, which posted a first-quarter loss, will meet its full-year sales forecast because of weak demand in the United States and Europe.

Vestas said last October it would cut 3,000 jobs and shut five plants. Its shares have tumbled nearly 45 percent in the past year and are down some 12 percent so far in 2011.

Vestas shares, which are traded at the Copenhagen stock exchange, closed at 154.60 Danish crowns before Chanos' comments. First Solar's shares fell 2.64 percent on Wednesday.

DAVID EINHORN, GREENLIGHT CAPITAL

IDEA: buy Dutch insurer Delta Lloyd NV

Einhorn also sent Microsoft's stock higher in after-hours trading after he recommended the company's board replace its Chief Executive Officer Steve Ballmer. His continued presence is the biggest overhang on Microsoft's stock, Einhorn said. He particularly criticized Microsoft's search business, saying it is time the company consider strategic alternatives in that area.

BILL ACKMAN, PERSHING SQUARE CAPITAL MANAGEMENT

IDEA: buy Family Dollar Stores Inc

Ackman said Family Dollar, which has more than 6,880 discount stores in 44 U.S. states, has been able to narrow the gap with its main competitor, which should result in very meaningful outperformance for the company.

He also said the company could become an attractive leveraged buyout target.

Shares of Family Dollar, which closed on Wednesday at $54.82, rose 1.4 percent in after-hours trading following Ackman's comments.

DINAKAR SINGH, TPG-AXON CAPITAL

IDEA: buy Sprint Nextel and Orkla Asa.

Singh said Sprint Nextel's shares are cheap, and sees an upside of 40 percent to 70 percent for them. He says a lot of investment in the company is under way, as he believes the government is focused on making sure Sprint stays a viable competitor after the merger between AT&T and T-Mobile.

Sprint shares closed 0.51 percent higher at $5.87.

He is also positive on the Norwegian conglomerate group Orkla, whose line of products ranges from food to metals.

PHILIP FALCONE, HARBINGER CAPITAL PARTNERS

IDEA: buy Crosstex Energy

Shares of the pipeline operator soared 11.3 percent to close at $10.16 after Falcone said they could rise to $18-$20.

Falcone, whose Harbinger Capital owns about 9.8 percent of Crosstex, expects the company's earnings before interest, taxes, depreciation and amortization to climb to at least $230 million this year from $182 million in 2010.

He also said he expects wireless broadband company Lightsquared to go public in the future.

BOB HOWARD, KKR & CO

IDEA: buy WABCO Holdings Inc and HSN Inc.

Shares of WABCO Holdings, a supplier of safety and control systems for commercial vehicles, spiked more than 3 percent after Howard said they are worth almost $100. They closed 3.12 percent higher at $68.03.

Shares of HSN, a teleshopping and e-commerce operator, ended 5.14 percent higher at $32.71 following his comments.

JEFF ARONSON, CENTERBRIDGE PARTNERS

IDEA: buy CIT Group Inc

With $12 billion in cash, the business lender company run by former Merrill Lynch Chief Executive John Train could buy a traditional bank or become an acquisition target, Aronson said, citing HSBC and Wells Fargo as logical buyers.

CIT shares closed 1.9 percent higher at $41.64.

STEVE EISMAN, FRONTPOINT FINANCIAL SERVICES

IDEA: buy property-casualty stocks, such as insurance brokers and large reinsurers.

ACTIVIST INVESTOR CARL ICAHN

Icahn plugged Icahn Enterprises LP. The billionaire investor said he would like to keep taking over companies and he would like to do it in a friendly manner.

(Reporting by Svea Herbst-Bayliss and Matthew Goldstein, compiled by Walter Brandimarte; editing by Matthew Lewis and Andre Grenon)

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