Utilize the input text as a context reference, choose the right relationship between Cinven and private equity from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

City sources named the private equity groups BC Partners, Cinven and KKR as possible buyers, although it is unclear whether any of those firms will pursue takeover bids.

Answer: product_or_material_produced