there are really a lot of choices.
1). CFA...3 years.
2). MFE...full time 1 year NTU, part time 2 year NUS.
3). MBA... INSEAD 1 year full time. US MBA 2 years, UK 1 year full time.
4). Ph.D... NUS 3 year - 5 year part time
5). Master... NUS 1-2 year part time in math, computational science. or economy...
....
there are just plenty or choices. But first, what is the natrual of your current job and what does it need.