'pro-bank' originates from the Latin prefix 'pro' (meaning 'for') combined with 'bank', which comes from Old Italian 'banca' (meaning 'bench', used for moneylenders).

'bank' passed into English via Middle English from Old Italian 'banca' (bench/moneylender's table); the modern compound 'pro-bank' is a recent English formation using the Latin-derived prefix 'pro-' attached to the noun 'bank' to express being 'for' banks.

Originally, 'pro-' simply meant 'for' and 'bank' referred to a bench or the place of moneylenders; together in modern usage the compound has come to mean 'in favor of banks' or 'supporting banking interests'.