Because the bid/ask at the time of that sale was .067 X .0675 so they either had a limit sell or entered a market order to sell and a MM picked up those shares for .0021 cheaper than they were being sold at the time. If that individual would've used a limit sell at .067 then they would not have sold for .0649. The unwritten rule of trading on the OTC, use limit buy and sell orders because you will get a fill or sell under/over the bid/ask quite often!