I was in another stock similar to nnlx pps years ago where trades as low as .0001 would go through quite a few times despite the bids being 2-5c pps

this upset a lot of longs - a broker told me these were in-house trades within a brokerage-

there is often a somewhat similar problem with all or none trades-when I traded penny stocks I used to use an AON order so I wouldn't end up with just a few dollar trade, which is fairly common in penny land

but my bids would often be overlooked- a broker said all or none orders could only be seen by the broker where they were placed-so only could be filled in-house at that brokerage

imagine then trying to trade one of the thousands of gray stocks where you have to guess what the bids and asks are because there is no mm and mm's and brokers are not allowed to publish quotes for such stocks