This is why sony stock went up.

http://finance.yahoo.com/news/sony-assess-spin-off-proposal-195826613.html

"Sony Corp is considering evaluating a proposal from top shareholder Third Point LLC to spin off part of its movie and music business, Japanese daily Nikkei reported.

Sony's U.S. listed shares rose 9 percent on Tuesday on the New York Stock Exchange.

Billionaire hedge fund investor Daniel Loeb last week called on the company to spin off its lucrative entertainment arm, setting the stage for a clash between his activist Wall Street fund and management at the Japanese electronics maker.

Sony declined to comment when contacted by Reuters.
Loeb said his Third Point hedge fund had accumulated a little more than 6 percent of Sony's shares - a stake worth $1.1 billion - making it the largest stakeholder in the inventor of the Walkman portable music player and Trinitron TV.

Sony shares were trading at $22.87 in afternoon trading."

Wouldn't the announcement of a new product have a positive effect on stocks?

Probably because Microsoft had the chance to bring it and failed pretty hard.

Not necessarily. Microsoft is so massive that a product like Xbox One isn't going to make a big impact. Strategic partnerships and shifts in markets impact Microsofts stock way more than individual products.

Microsoft stock is currently on a massive high and a new gaming console isn't going to push it up or down significantly. 

It did the same thing with the Ps4 reveal, Sony stock drop and microsoft and Nintendo rised.

It always like that, the stock drop in front of new and changing horizon.

If you are at the bottom the only way to go is up

Disappointing xbox reveal :/

No. everyone knew the next product will be announced and imagination is always better than reality. So stocks dropping on the reveal of new products, except nobody expected something new.

We'll see how long this lasts, but the investors may have greater confidence in Sony to do well. The Microsoft stock is pretty much flat

Apparently Nintendo's stock also rose 2% to $11.79

http://mynintendonews.com/2013/05/21/nintendo-and-sony-stock-prices-rise-after-xbox-one-announcement/?utm_source=dlvr.it&utm_medium=twitter