“If you can't see the Bid and Ask you just put in a Limit Order for the number of shares you want to buy or sell and the price, and you either get filled in full or not“
Yes, but when that is the only way shares can be bought and sold, it affects liquidity. There is also no requirement for best execution so it becomes kinda random.
You could have a buy order in at 0.15 and see a trade go off at 0.10.
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