IP lawyer here (NOT <i>your</i> lawyer). A polite, friendly cease-and-desist letter might well do the trick — if it really is the First National Bank of Pittsburgh PA that's using the name.<p>And a <i>funny</i> C&D letter can help get your app some exposure, as evidenced by some examples from recent years. [0]<p>In that vein, maybe you could come up with some kind of publicity stunt, the way a small aviation services company did in the early 1990s when Southwest Airlines started using the slogan "Just Plane Smart," pretty close to the small company's slogan "Plane Smart." The two CEOs — one a late-30s weight-lifter, the other the aging, hard-drinking smoker Herb Kelleher — arm-wrestled for the right to use the slogan, in a big, staged event for charity. The weight-lifter won, but gave Southwest the right to use the name anyway in exchange for a donation to charity — and the small company reportedly got a significant bump in revenue from the publicity (and probably from aviation-industry approval of the clever way they'd handled the matter instead of running to the courthouse). [1]<p>Finally, you might consider offering to sell FNB the name and changing your app's name — years ago I had a client that provided very-high-dollar specialty software in a niche industry; the client sold its name to a British multinational conglomerate that approached the client out of the blue because their chairman <i>really</i> wanted the name.<p>BTW, common-law trademark rights can be just as enforceable in the end, even though a federal registration provides significant procedural advantages.<p>(Disclosure: In addition to not being <i>your</i> lawyer, I haven't practiced trademark law in many years.)<p>[0] <a href="https://www.stites.com/resources/trademarkology/friendly-foes-trademark-cease-and-desist-letters-are-filled-with-humor-these-days" rel="nofollow noreferrer">https://www.stites.com/resources/trademarkology/friendly-foe...</a><p>[1] <a href="https://www.upworthy.com/in-the-90s-two-companies-were-using-the-same-motto-they-arm-wrestled-to-see-who-got-to-keep-it" rel="nofollow noreferrer">https://www.upworthy.com/in-the-90s-two-companies-were-using...</a>