I just read an article that the founders of Twitter reportedly turned down a half-billion dollar buyout offer from Facebook.*
I know there are ways to make money betting on the success of a company, but is there any way to bet against a company that isn’t publicly traded?
*I think they really should have a conversation with Mark Cuban and ask if he regrets not holding out for more money when Yahoo! bought Broadcast.com.
For a publicly traded company, there is an option to short-sell stock or to buy stock options. Both can yield a profit to you if the stock goes down.
Twitter is still private, however. About all you can do is look for a competitor that would benefit if Twitter failed.
There are other services for microblogging, but not many. I don’t know what advantage any of them have over Twitter, if any, but here’s a little about them: Microblogging - Wikipedia
Find somebody who’s willing to bet against you, and sign a contract. You’ll need to define the exact terms of the bet in significantly more detail, but I’m sure there’s someone out there willing to take it as long as it’s reasonable.
You can suggest it at intrade.com