http://www.wilmott.com/messageview.cfm?catid=16&threadid=67996&STARTPAGE=1
The psychological pressure can be huge. There are a lot of people in Ph.D. programs who have never had the experience of being rejected, because since kindergarten their history has been “pass the test” go to the next level, and the system they have been in has been somewhat rational in which if you don’t make it to the next level, it’s because of something “bad” you did. Once you got your Ph.D., you are no longer in the world (even if you stay in academia), and it is a huge transition to make to realize, that you are going to fail and be rejected, even if you are very, very good. In a situation in which you have to keep knocking on doors and getting rejected time and time again is new, and something that most people have to deal with is the (justified) fear of rejection, humiliation, and failure.
Be ready, be flexible, so that you are ready if there is a massive burst of hiring in two months or if Wall Street ends up a dying industry. One thing that this means is that it helps if you don’t have too fixed an idea of what you want to do. If you say ‘I want to be a quant” then you run into the problem in that there may be no jobs whatever this quant thing is. On the other hand, if you say “I want to do cool things with math and computers” your options vastly increase.