If I did not sign promotion bonus document, my career would be over. Is this duress?
No. The premise is hardly true or even logical, and what you describe falls short of duress. Not every imbalance of bargain power implies duress.
First, it seems that you could have declined the bonus, thereby preempting the sanction/remedy for leaving within 12 months.
Second, it seems hard to prove (and unrealistic) that your career would have been over if you refused to sign the document. The employer can easily refute that allegation by pointing out that there are many others who did not sign that employer's document and yet work elsewhere as investment bankers. You would need certain, additional context to reasonably allow for a conclusion that your career altogether depends on what happens with this single entity.
Third, your mention that "the bonus mitigates the horrendous weekly hours" reinforces the idea that signing the document was your preference (namely, for the purpose of obtaining some additional, non-compulsory stimulus) rather than employer-inflicted duress.
The rationale and decision for acceptance of those conditions reflects that you knowingly exercised your freedom of contract. A party is not entitled to void a contract only because he belatedly changed his mind about conditions of which he was aware beforehand.