Actually, I think it is better said "It is who knows you".

Many have thought that the best way to get somebody to know you is through a resume. Really, the best way is through contacts. In my long career, I have had three "starting points" where I got a job without using my contacts network. And that was without really being conscious about it.

If you are in the programming profession (don't know about trading) then today's best way is to put up a web site with a project that you are building. Show your stuff.

(I can't believe how far off the rails this whole discussion has gone. And we aren't even to the "cover letters are more important that resumes" discussion.)