It totally depends on the company and position you do. For our program, we mostly learn/use
C++,
Python and R.
For quant industry:
-> if you are a Quantitative/High-Freq Trading Developer, you need to have strong CS background, and will have to know
C++/C# or Java very well, especially scientific computing, high-performance, multi-threaded applications, etc. (I am not an expert in this field)
-> if you are a Desk Quant/Strat, you will very likely use
C++/
Python a lot. (Our program has high focus on this)
-> if you are a Trader / Portfolio Manager, you may use some VBA /
Python / Matlab / R.
-> if you are a Data Scientist, you must be good at R/
Python.
Some companies use Scala. SQL and KDB/Q are very common for database applications. As I said, it totally depends on the position and the company.