There is no such thing as an efficient market. Prices are always moving, thus prices are hardly ever efficient. If everyone agreed a price was efficient then no trades would take place. Price movement is caused by peoples different valuation of assets. If I sell you a watch for $10, then you have a higher demand for the watch than your $10. I have a higher demand for the $10 than my watch. Only because of this unequal valuation of money and goods does a transaction take place.
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