Ask HN: How can both Verizon and Comcast be down?
Both Verizon and Comcast are currently reporting outages in parts of Silicon Valley at the same time.
WTF
WTF
The question doesn't respect reality. There can be oligopolies or cartels with numerous participants. There can be sharp competition with only two participants.
Oligopoly (or its demand-side complement, oligopsony), can be defined by economic characteristics, or other criteria.
I'd strongly recommend the work of Joan Robinson on imperfect competition generally. There's also a whole political element to such questions --- economic power is a form of power, and monopoly/monopsony oligopoly/oligopsony both represent different concentrations of such power.
The issue is that oligopoly isn't defined in terms of size but by behaviour.
For a few examples of larger cartels (effectively: oligopolies):
The LIBOR price-fixing scandal. From at least 1991 until 2012, the London Inter-bank Offered Rate (LIBOR) was manipulated by numerous large banks. The investigation ultimately extended to 20 banks in three countries. <https://en.wikipedia.org/wiki/Libor_scandal>
The Streetcar Conspiracy. Between 1938 and 1950, operating largely through National City Lines (and subsidiaries American City Lines and Pacific City Lines) operating under direction and coordination by at least nine corporations (the number indicted in 1947). These included Firestone Tire, Standard Oil of California, Phillips Petroleum, GM, and Mack Trucks (convicted). <https://en.wikipedia.org/wiki/General_Motors_streetcar_consp...>
OPEC. The Organisation of Petroleum Exporting Countries was formed in 1960, and includes 13 countries, all national producers of oil. It has strongly influenced, and at times effectively controlled, global petroleum markets and prices. It's only one of many such cartels or monopolies in the history of oil extraction. <https://en.wikipedia.org/wiki/OPEC>
The De Beers Diamond Cartel. This is controlled by a single company (the De Beers group), but operates through many thousands of diamond wholesalers and retailers. This is the largest cartel I can think of which readily comes to mind (and I've found that search tends to be dominated by extralegal narcotics organisations), but would suggest that upper limits tend to be high. <https://www.stepbystep.com/The-History-Behind-the-DeBeers-Di...>
The interrelationships between corporations generally can be quite interesting, and may or may not constitute an oligopoly or cabal of some sort. This has been observed generally for boards of major US corporations, which tend to share directors, the cadre of top CEOs, keiretsu and chaebol in Japan and Korea, respectively.
Among the specific quantified measures I'm aware was a 2011 study by the Swiss Federal Institute of Technology (Zurich), which identified of 43,000 transnational corporations a locus of 147 key companies:
When the team further untangled the web of ownership, it found much of it tracked back to a “super-entity” of 147 even more tightly knit companies – all of their ownership was held by other members of the super-entity – that controlled 40 per cent of the total wealth in the network. “In effect, less than 1 per cent of the companies were able to control 40 per cent of the entire network,” says Glattfelder. Most were financial institutions. The top 20 included Barclays Bank, JPMorgan Chase & Co, and The Goldman Sachs Group.
As to concerns over this, one that the research team identified:
Concentration of power is not good or bad in itself, says the Zurich team, but the core’s tight interconnections could be. As the world learned in 2008, such networks are unstable. “If one [company] suffers distress,” says Glattfelder, “this propagates.”
<https://www.newscientist.com/article/mg21228354-500-revealed...>
The study itself is "The Network of Global Corporate Control" by Stefania Vitali, James B. Glattfelder, and Stefano Battiston. <https://arxiv.org/PS_cache/arxiv/pdf/1107/1107.5728v2.pdf> (PDF)