Investment banking and trading are not the same thing - unless you are already a good candidate for banking (straight As from school, first or at minimum 2:1 from a top uni, relevant work experience), trading your own account isn't going to help get a job.
If you mean moving from prop or own account to a trading role in an investment bank, probably depends on your strategy - as has been said, they are meritocracies, so if you have a great track record, and your strategy is scalable enough to make working for a bank appealing, they might look at you. Most likely though, you'll do better by trading own account or getting backed by a prop firm - most of the trading done in banks is rather different from that done by prop guys and own accounters.