A method of and system for distributing a content item, having a plurality of segments. A composite content item is created by concatenating segments from different content items from different agencies. A segment of the composite content item may or may not already comprise a previously embedded segment watermark carrying a previously embedded segment payload. The method comprises determining if the segment already comprises a previously embedded segment watermark, and if so, logging the previously embedded segment payload in a watermark transaction log associated with the new segment payload; otherwise, embedding the new segment payload as a watermark in the segment. In the case that the segment already comprises a previously embedded segment payload, the previously embedded payload is logged in a watermark transaction log, and the previously embedded segment payload is replaced with a new segment watermark that represents the new segment payload. A method and system for monitoring the distribution of a content item using a transaction log.