Considered the “crown jewel” keyword in any TLD, the domain name Sex.co changed hands in early January of this year, according to historic WHOIS data from DomainTools.
While it probably did not reach the reported sale of Sex.xxx for $3 million USD, Sex.co probably fetched a pretty penny in a yet undocumented sale.
Its current registrant, Quattro Media Co., is based in The Netherlands; while there is a semi-developed web site that points to adult personals, the domain is also listed for sale at Sedo.
Since their launch in July 2010, dot .CO domain names have become widely adopted by start-ups and corporations, as effective, brandable alternatives to .com.