It’s tempting to believe that at the third stage interview you were home and dry and that this meeting was a short step to the final job offer. Clearly, for you, this was not the case which is why a job candidate must always understand the hiring process for the job role they are applying for and the personalities of the stakeholders involved in the process from the outset, as anything can and does go wrong in interviews, leading to interview rejection.
Hiring processes can take many forms and formats. Some organisations, depending on the role and industry have way more stages than three interviews and although you don’t say, it sounds as if you believe this interview was to be the final stage and since the previous interviews went well, you expected a similar positive outcome. Who knows why you weren’t well received? There could be many reasons; none of which may be to do with you or your performance – so don’t over think it.
In this situation, there is little you can do, as you were still participating in the hiring process. And, unfortunately, interview rejection is part and parcel of the candidate experience until the organisation makes a formal job offer.
So what can you do? You can write to the organisation and ask for feedback but you should temper your expectations as you may not get anything specific or particularly useful information in return.
Or you can chalk up this situation as experience and ensure that the next time you are called for an interview you get as much information about the personality and expectations of the individuals who are conducting the interview so you know what you will be dealing with so you can prepare and act accordingly.
This post has been adapted from answer posted by WorkWisdom on http://www.quora.com