Even if the targetted promo piece does not mention credit, there's an indirect fair lending risk.
Almost all banks favor depositors over non-depositors when granting credit and pricing credit products. The goal of the promotion under consideration is to increase the number and percentage of wealthy depositors. Other residents within your service area will not get this opportunity to become a depositor. In effect, you are redlining them.
Later, when these individuals show up as loan applicants, they are treated less favorably than those who reside in high-wealth neighborhoods to which you have targetted your promotions.
_________________________
...gone fishing.