There is no one-size-fits-all answer to this question, as different languages may be better suited for different aspects of banking software development. However, some popular programming languages used in the banking industry include Java, Python, C++, and SQL. Java is particularly popular for developing server-side applications, while Python is often used for data analysis and visualization. C++ is known for its speed and efficiency, making it popular for applications such as high-frequency trading. SQL is used for querying and manipulating data in databases.