Dan Loeb's Third Point hedge fund sent out a letter to investors today.

On Yahoo! (Nasdaq: YHOO), Loeb noted selling about two-thirds of his stake in the company while removing three nominee's to the company's board. Loeb comments, Since Third Point initiated its position, over $15 billion of value has been created, growing the company’s market cap from $15 billion to $30 billion today, while over $5.2 billion of cash has been returned to shareholders. Since Third Point made “The Case for Alibaba” in our original investment presentation, our Fourth Quarter 2011 Investor Letter, and on our valueyahoo.com shareholder advocacy website, consensus Wall Street estimates for Alibaba’s value have increased from $20 billion to over $80 billion.

Loeb also noted Third Points equity position in Sony Corp. (NYSE: SNE). He has been pushing the company to partially list its Entertainment business to make up for shortfalls in the Electronics unit. He comments, ...the Sony management team installed last April seems to have broken a long string of challenged leadership and has started to make some difficult decisions in the Electronics business by reducing overhead and cutting the number of products offered. Highly-regarded CEO Kazuo Hirai deserves plaudits for the green shoots increasingly visible in Electronics. Sony’s Xperia Z smartphone is a hit, and new product momentum has built meaningfully over the last few months while competitors have been losing ground.

Entertainment has trailing twelve month EBITDA margins that are 700 basis points below peers in the Pictures division and 380 basis points below peers in the Music division, despite the fact that each is an industry leader in revenue terms, Loeb said. If Entertainment achieved peer margins, EBITDA could increase nearly $800 million to just over $2.0 billion.

Loeb also like the launch of Sony's PlayStation 4 in June, thinking it will take market share from Microsoft's (Nasdaq: MSFT) Xbox and Nintendo's Wii. The visible improvement in Sony’s new products has caused us to rethink our approach to valuing Electronics, Loeb said. The Game and Mobile Products divisions are now poised to join the Devices business as meaningful profit contributors, while the Television business is becoming only a marginal drag.

Loeb thinks Sony's Entertainment division remains poorly managed and is bloated. While the Pictures unit is anchored in higher-margin international cable networks and TV production, the film business profitability is negligible. This makes apples-to-apples comparisons with peer film studios (which lack the benefit of cable networks in those segments) even more unflattering. Nevertheless, we believe the film unit possesses considerable library cash flow value, currently masked by poor new production profitability, as well as significant asset value in its Culver City lot, he said.

On Shinzoe Abe, Loeb thought that Sony could benefit from the First and Second Arrows of his economic plan -- that a weaker yen combined with fiscal stimulus would drive better margins and EPS at Sony -- but now thinks that the company is an ideal candidate for the third arrow.

Sony is down 1.2 percent Monday.