Yes. It is no different than placing a market bid or ask. If the current bid is 100k shares at .29 for example and someone wants to sell 200k at no less than .28 that person can simply enter 200k at .28. If the bids/asks stay the same the seller will get .29 for their first 100k shares and then the remainder (100k in this example) will hopefully get sold at .285 and so forth, all the way down to as low as .28. If all 200k aren't disposed of, the remainder would become the ask at .28. The market simply displays the highest bidder and the lowest seller. There are many reasons why someone would be willing to "pay more" than the lowest ask or why someone would be willing to sell lower than the highest bid. I have done so before simply because I knew the stock was going to run away from me in either direction. As I said, its similar to a market order which simply buys or sells until completion of all the bought or sold shares at ANY price until the entire order is filled. Hopefully this helps, hard to explain.