UBS traders were told about some new, compulsory sartorial rules this morning.

Equity sales team members were told in a memo that "suits are now mandatory" at the office, Dealbreaker reported.

Apparently swaps and quants already made the change and equities are next.
The new dresscode is apparently being mandated by the bosses back in Switzerland with a goal to "re-establish credibility and a sense of professionalism."

http://www.businessinsider.com/ubs-traders-get-memo-suits-are-now-mandatory-2011-6