Billed as one of the largest mergers in PR history, Ketchum announced plans to merge with Omnicom's Pleon, a communications and consultancy shop headquartered in Dusseldorf, Germany. Ketchum has worked with Pleon for clients before, said Ray Kotcher, senior partner and CEO at Ketchum. Talks about a merger between the two companies began a year ago. The companies began the integration process in July, and hope to have completed the merger by the end of the year, according to a Ketchum spokesperson. Financial terms of the deal were not disclosed.