trademark My domain name has been service marked?

I have a somewhat similar situation to a recent post but this involves a service mark a big US financial company is using as one of many taglines in their advertising. I registered this dotcom domain in 08; well before they service marked it. It has never been developed but is currently being offered for sale.

Can I get some answers/opinions regarding the best course of action to not get into any UDRP/ownership problems. Thanks.