Certification like FRM or CFA are quite popular with banks or FM.
Alternatively look at the job description of the roles you are interested in, and see what qualifications or skills they need and work towards that.

There are many functions in the banking and financial industry, you have to be clear of which and what you want. If you are unsure, go lookup and search at some of the short courses conduct by local universities on financial markets and instruments, etc. Get yourself familiar with the industry, and understand the different functions.

And if you don't care about the functions but just want to gain exposure working in the bank, another option is to look for temporary roles or short contract roles (which are usually created to tide over sudden shortage of manpower such as maternity coverage). You can easily search and find these in efinanical page, many of which are via job agents. Try to apply, if they reject, talk to the agents and tell them your desire to find a job in the industry and is willing to accept temp or contract roles. Ask them to keep you posted.
However, do note usually big banks and FMs are quite specific on their requirement for such roles and will normally require for people with prior experience, hence try to gain some experience by starting out in smaller foreign banks or small FMs.