Epiphany is a search marketing agency which deals in both pay-per-click advertising and search engine optimisation across 25 countries.
The agency says it hopes to help Yorkshire Building Society tap in to the 10 million consumers searching for financial products each month.
Epiphany managing director Shane Quigley said: "Our expertise is ensuring that when relevant financial product phrases are entered into search engines, Yorkshire Building Society is at the top of the listings."