The first rule about becoming a managing director at Morgan Stanley is you don't talk about how much you want to become a managing director at Morgan Stanley.

The Wall Street bank last week promoted more than 150 of its staff to the coveted rank, up around 9% on 2016. Unlike its rival Goldman Sachs, which moved to a biennial MD promotion round in 2015, Morgan Stanley still bumps people up every year — but there are strict rules on making the grade.