It can happen in more rare cards. Lets assume there is only handful of people who are willing to sell Beltram Cr for say - 160k.
If most of them take a weeks vacation and there is only few copies in the market for a little over 160k - the price jumps very easily if someone gets those few copies.
It is possible because lack of quaranteed supply.
Same effect can happen on cards that are not marketwise very interesting. People simply forget to set their copies for sale and there is temporary lack of supply in the market -> few normal buys and the price is tripled. This will change naturally as soon as some of the holders spot the opportunity to sell for great profits (less than the leaped price, but way above previous price).
This happens even in normal market and it doesnt require market manipulation to happen (but it happens often because of market manipulation, as these opportunities are often exploited because they are potentially profitable.).
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