Ann: 2018 AGM Presentation, page-49

Billy, all it takes on the NASDAQ is for a Market Maker(broker) to short the stock down to create liquidity. I think that is still the case. When there is tiny or no volume the MM is legally permitted to naked short till a level of liquidity is reached, ie stock is available for trades. Sometimes they will drive the price down to pick up stop loss sell points. This makes money for the MMs, who pick up stock at the lower price to fill orders(when they had no stock to sell) they sold at the higher level, turning a profit every time. eg they sell stock they don't have for $1.50 then buy real stock for $1.00 to fill the order after the price drops, turning a tidy profit.That is how I understand it. If you think that market sounds rigged against small investors I agree with you. Even if there are no real sellers the MM's sell fake stock. That does not happen on the ASX for small companies as far as I know, but no matter, the manipulated NASDAQ market seems to be linked to the ASX price and it also drops. I think brokers have 7 days after the trade (T+7)to settle the account, although I see many hold off for a much longer time. The term there is fail to deliver(FTD)

Here is a NASDAQ investor venting off about the short walkdown if you are interested http://bobvisse.com/tag/short-selling/