There is a miscommunication here, arising from the fact that bunderbunder thinks that 'Citigroup' is an entity, and is clearly both a market maker and has clients, whereas you (and other professionals in the field) think 'Citigroup's equity option market making desk' and 'Citigroup's prime brokerage division' are entities, and are clearly only one of those things each.

People at a distance from organisations see them as monolithic. People closer to them see them as coalitions of distinct entities.