The Mercado project explores a services marketplace that provides a business-over-the-Internet environment, where a business user can specify business tasks and run a business lifecycle using services provided over the Internet. Our objective is to build business assurance techniques within Mercado so that customers can be confident that it is safe to make the success of their business dependent on such marketplaces and services. To uncover requirements on data exchanged in such marketplaces, we perform a threat analysis on a fictional business that runs a marketing campaign using online business services. We detail specific customer requirements and research areas uncovered by the identified risks. We position these research areas in a service environment that significantly differs from traditional enterprise IT environments.