Respectfully, if you are asking that question you probably don't have enough info to warrant doing this unless you like to and can afford to gamble.

At this point yes, it would be pure gamble. I thought there might be objective information that could have come out of this post :) Then, I would take a rational decision.

If there is a rational decision based on publicly available information, it has almost certainly been priced in already. Honest advice: always be aware that it's gambling (and it seems you are). Look to index funds or similar for relatively stable growth.

Shorting a stock this volatile is an insane idea imo. You could wake up tomorrow and Microsoft decided to put a bid on Twtr and the stock prices gaps up so hard you lose your shirt.

If you want to short something like this, take a look at put options instead as your liability is explicit.

The question is: how many people are already doing something like this? The stock has already started to move down so unless there is more news on the way it may not move much in the near term.

4.85% of its float or 2.2 days of its average daily volume [1]. That compares with the S&P 500 SPDR's 2 days [2].

[1] http://shortsqueeze.com/shortinterest/stock/TWTR.htm

[2] http://online.wsj.com/mdc/public/page/2_3062-nyseshort-highl...

Don't short the stock. You'd buy options for strike prices your predict the security to reach. This limits your liability (unlike shorting a stock, which has unlimited liability).

pre-market it's down ~17%, so I think you missed your window.