Edward Herman and Noam Chomsky argued that five filters shape news reporting in mainstream media: financial ownership of media by wealthy individuals, reliance on advertising revenue, sourcing news from government and PR, vulnerability to negative responses ("flak") from powerful groups, and use of anti-communism/anti-terrorism as a frame against those threatening elite interests. Together these filters form a "propaganda model" that ensures media support for the political and economic status quo by marginalizing dissenting voices.