What is the relationship between Viacom and CBS in the context of the input sentence. Choose an answer from: 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.

The cost of credit-default swaps of media companies including CBS Corp. and Viacom Inc. also increased as investors grew skeptical about the health of the pay-TV industry.

Answer: parent_organization