I have an idea for a company and I want to share it with potential investors. I'm a bit concerned about my ability to protect the idea. Should I get them to sign an NDA? Would that scare investors away?
The short answer is NO!
Asking your investors to sign an NDA is impractical as most of them see dozens if not hundreds of ideas each years so they will never be able to manage their exposure if they have to sign an NDA for each idea they hear.
At the same time, asking an investor to sign an NDA is telling the investor that you are probably very concerned about sharing your idea and this fear has prevented you from validating your idea enough with the market.
I actually wrote a post about this a few years ago if you want to read a bit more - http://www.yanivnizan.com/2009/08/signing-nda-with-an-investor-good-idea-or-a-bad-one.html