I often trade on a site with a low amount of trades because I like how it gets less attention and it's more likely to pay out when I request funds. Yesterday I saw like 10 trades that went WAY below the current bid/sell spread. I have no idea how someone was able to manipulate the price down but I'm sure it's happening on other sites as well. Can you just put in buy and sells limit order at the exact moment and they'll get matched and ignore the better prices in the orders that are already out there? I did inform the owner and they said they would take action against the account that did it but I was like, wait, you needed me to tell you, you're not watching it yourself for stuff like that? WTF
Read this to see what happens if you trade on trivial exchanges:
https://bitcointalksearch.org/topic/m.4508190
In short: the exchange goes idle and there are too few users to cause a splash in the news when withdraw stops. Public ignores the event. Not any user of it can afford legal action. I have > 30 coins stuck there. There are who lost > 50 coins, have account revoked/disabled, and decided not to sue after all. (The exchange announces: withdraw stop because of power failure, will resume when power is back. And power hasn't been 'back' for 2 months.)