It's way to simple to look at a number and say "oligopsony". You'd need to look at how the market functions and how actors on it act. In this particular market

It's way to simple to look at a number and say "oligopsony". You'd need to look at how the market functions and how actors on it act. In this particular market: players make razor-thin margins (low single digits as mentioned before), and have regular price wars to fight over market share. It seems 5 is enough to keep players from making excessive profits.