Mainstream media (MSM) is a term and abbreviation used to refer collectively to the various large mass news media that influence many people, and both reflect and shape prevailing currents of thought. The term is used to contrast with alternative media which may contain content with more dissenting thought at variance with the prevailing views of mainstream sources.
The term is often used for large news conglomerates, including newspapers and broadcast media, that underwent successive mergers in many countries. The concentration of media ownership has raised concerns of a homogenization of viewpoints presented to news consumers. Consequently, the term mainstream media has been widely used in conversation and the blogosphere, sometimes in oppositional, pejorative, or dismissive senses, in discussion of the mass media and media bias.
The advent of the internet allowed the expression of a more diverse or alternative viewpoint which may contrast to mainstream media, to the point where the term mainstream media is seen in pejorative terms.
Lamestream media is a common pejorative alternative. Sarah Palin referred to "lamestream media", notably around 2009 during her participation in the Tea Party Express, in the context of what she perceived as media misrepresentation of the Tea Party movement.
Another term, originating on anonymous message boards, for the Mainstream Media is the acronym "MSM". The term is widely used by many on 4chan and Reddit, often as shorthand for the phrase "Mainstream Media".
In the United States, movie production is known to have been dominated by major studios since the early 20th century; before that, there was a period in which Edison's Trust monopolized the industry. In the early twenty-first century the music and television industries was subject to media consolidation, with Sony Music Entertainment's parent company merging their music division with Bertelsmann AG's BMG to form Sony BMG and Tribune's The WB and CBS Corp.'s UPN merging to form The CW. In the case of Sony BMG there existed a "Big Five", later "Big Four", of major record companies, while The CW's creation was an attempt to consolidate ratings and stand up to the "Big Four" of American network (terrestrial) television (although the CW was actually partially owned by one of the Big Four in CBS). In television, the vast majority of broadcast and basic cable networks, over a hundred in all, are controlled by eight corporations: News Corporation (the Fox family of channels), The Walt Disney Company (which includes the ABC, ESPN and Disney brands), National Amusements (which includes CBS Corporation and Viacom), Comcast (which includes the NBC brands), Time Warner, Discovery Communications, E. W. Scripps Company, Cablevision, or some combination thereof.
There may also be some large-scale owners in an industry that are not the causes of monopoly or oligopoly. Clear Channel Communications, especially since the Telecommunications Act of 1996, acquired many radio stations across the United States, and came to own more than 1,200 stations. However, the radio broadcasting industry in the United States and elsewhere can be regarded as oligopolistic regardless of the existence of such a player. Because radio stations are local in reach, each licensed a specific part of spectrum by the FCC in a specific local area, any local market is served by a limited number of stations. In most countries, this system of licensing makes many markets local oligopolies. The similar market structure exists for television broadcasting, cable systems and newspaper industries, all of which are characterized by the existence of large-scale owners. Concentration of ownership is often found in these industries.
In the United States, data on ownership and market share of media companies is not held in the public domain.
Recent media mergers in the United States
Over time the rate of media mergers has increased, while the number of media outlets has also increased. This has resulted in a higher concentration of ownership, with fewer companies owning more media outlets. In 1983, 90% of US media was controlled by fifty companies; today, 90% is controlled by just six companies.
The "Big Six"
|The Big Six||Media Outlets||2018 Revenues|
|Comcast||NBCUniversal (a joint venture with General Electric from 2011 to 2013): NBC and Telemundo, Universal Pictures, Focus Features, 26 television stations in the United States and cable networks USA Network, Bravo, CNBC, The Weather Channel, MSNBC, Syfy, NBCSN, Golf Channel, E!, Chiller, Olympic Channel, and the NBC Sports Regional Networks. Comcast also owns the Philadelphia Flyers through a separate subsidiary.||$94.5 billion |
|The Walt Disney Company||Holdings include: ABC Television Network, cable networks ESPN, the Disney Channel, A&E and Lifetime, approximately 30 radio stations, music, video game, and book publishing companies, production companies Touchstone, Marvel Entertainment, Lucasfilm, Walt Disney Pictures, Pixar Animation Studios, the cellular service Disney Mobile, Disney Consumer Products and Interactive Media, and theme parks in several countries. Also has a longstanding partnership with Hearst Corporation, which owns additional TV stations, newspapers, magazines, and stakes in several Disney television ventures.||$59.4 billion |
|News Corporation*||Holdings include: the Fox Broadcasting Company; cable networks Fox News Channel, Fox Business Network, Fox Sports 1, Fox Sports 2, National Geographic, Nat Geo Wild, FX, FXX, FX Movie Channel, and the regional Fox Sports Networks; print publications including the Wall Street Journal and the New York Post; the magazines Barron's and SmartMoney; book publisher HarperCollins; film production companies 20th Century Fox, Fox Searchlight Pictures and Blue Sky Studios.
(*) As of July 2013, News Corporation was split into two separate companies, with publishing assets and Australian media assets going to News Corp, and broadcasting and media assets going to 21st Century Fox.
|$39.4 billion ($9 billion News Corp  and $30.4 billion 21st Century Fox )|
|WarnerMedia (AT&T)||Formerly the largest media conglomerate in the world, with holdings including: CNN, the CW (a joint venture with CBS), HBO, Cinemax, Cartoon Network/Adult Swim, HLN, NBA TV, TBS, TNT, truTV, Turner Classic Movies, Warner Bros. Pictures, Castle Rock, DC Comics, Warner Bros. Interactive Entertainment, and New Line Cinema.||$28.9 billion |
|CBS Corporation||Holdings include: CBS Television Network and the CW (a joint venture with Time Warner), cable networks CBS Sports Network, Showtime, Pop; 30 television stations; CBS Radio, Inc., which has 130 stations; CBS Television Studios; book publisher Simon & Schuster.||$14.5 billion |
|Viacom||Holdings include: MTV, Nickelodeon/Nick at Nite, VH1, BET, Comedy Central, Paramount Pictures, and Paramount Home Entertainment.||$12.9 billion |
Although Viacom and CBS Corporation have been separate companies since 2006, they are both partially owned subsidiaries of the private National Amusements company, headed by Sumner Redstone. As such, Paramount Home Entertainment handles DVD/Blu-ray distribution for most of the CBS Corporation library.
American public distrust in the media
A 2019 Gallup poll found that Americans remain largely mistrustful of the mass media. Between 2017 and 2019, 41%-45% of respondents have had "a great deal" or "fair amount" of trust in newspapers, television and radio to report the news "fully, accurately and fairly." Distrust had increased since the mid 2010s when Americans were already more negative about the media than they had been before 2004.
Throughout 2016, Google and Facebook had been targeted to disperse a substantial amount of fake news, with the aim, it was claimed, of confusing Americans about various topics. Following the victory of Donald Trump in the 2016 presidential election and during the campaign, Americans who supported Hillary Clinton were especially enraged about the noticeable amount of fake news about the election on the two websites. Facebook was targeted to some degree in order to sway the American people with a particular agenda during the electoral cycle, although the chief executive of Facebook, Mark Zuckerberg stated that "Facebook did not have a role in the recent presidential campaign".
In the UK, during 1922, after the closure of many radio stations, the British Broadcasting Company started its first daily radio transmission and started to grow an audience. Later that year John Reith, a Scottish engineer, would be appointed the first General Manager for the BBC. Later on January 1, 1927 the BBC was fully established by Royal Charter and renamed the British Broadcasting Corporation with Reith as the first Director-General. During November of 1936 the BBC began to expand into television broadcasting and was the first broadcaster to start the trend of a regularly scheduled TV service. 
Today the BBC is one of two chartered public broadcasting companies in the United Kingdom. The second is ITV, Independent Television, which was established in 1955 as the first public commercial television company after the Television act of 1954 in an effort to break up the monopoly the BBC had on television broadcasting, gaining fifteen regional broadcasting licenses in less than twenty years.  Today the BBC and ITV are the two free to air digital services offered to everyone in the United Kingdom and each others biggest competitors. The BBC has nine national television channels, BBC three, the first channel to switch from television to online, an interactive channel, ten national and forty local radio stations, BBC Online, and BBC Worldwide. ITV currently holds thirteen of the fifteen regional broadcasting licenses in the United Kingdom that carries their multiple channels including ITV, ITVhub, ITV2, ITVBe, ITV 3, ITV4, CITV, ITV Encore, Britbox, a video-on-demand service in collaboration with the BBC to bring British television content to the United States and Canada, and Cirkus, their own video-on-demand service. 
|Wikiquote has quotations related to: Mainstream media|
- Agenda-setting theory
- Alternative media
- Big Three television networks
- Concentration of media ownership
- Corporate media
- Fake news
- Freedom of speech
- Freedom of the press
- Lists of corporate assets
- Local News Service
- Media bias
- Media conglomerate
- Media cross-ownership in the United States
- Media democracy
- Media imperialism
- Media manipulation
- Media proprietor
- Media transparency
- Monopolies of knowledge
- Network neutrality
- Old media
- Partido da Imprensa Golpista
- Politico-media complex
- Prometheus Radio Project
- Propaganda model
- State controlled media
- Telecommunications Act of 1996
- Western media
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