Generics are still susceptible to WIPO cases, some are succerssfully defended while others (more times than not) are lost.
One good example would be Windows.com. If you own that domain and use it to promote windows (home windows, car windows, stained glass, etc..) there isn't a thing MS can do about it but once there is a computer related ad on the site, Microsoft has all the ammunition to not only file a WIPO but (due to their bankroll) have a good chance of winning it.
Unless your generic is something like OnlineBanking.com (or other generic that pertains to banking, not a "generic" like fleet.com), you might be safe.
On a different matter, if the bank is directing people to your site to log in, this is a catastrophic security risk. Even if people are typing it in (say Onlunebanking.com as opposed to onlinebanking.com) you are still at risk if you ever ask for a login and password - that could be viewed as an attempt at phishing and get you in huge trouble (unless you make it overly clear that you are not onlinebanking.com).