We might also consider the Stock Exchange or the market in Government stock as quite close to perfect competition: all the traders are highly knowledgeable and no one trader can affect the market price. Even so, there are bigger barriers to entry since traders must satisfy a quite large number of rules before being let loose on the floor of the Exchange or in the virtual-exchange. For these reasons, I think that financial markets are not perfect, added to which is the problem of probity and legality affecting that market. Traders and dealers seem to be tended to simple dishonesty, insider dealing, and complex secret agreements etc.
The fact is that there are no examples of true perfect competition or anything close in the real world, because no producer wants to be in perfect competition - there are no profits in it. That's why companies advertise, claiming their goods are different and better; give volume discounts to attract big (i.e. more profitable) buyers; etc.
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