Is anything under $5 considered a penny stock.? There is a shorting rule on NYSE that you can't short them....anyone knows
if a stock is unmarginable then you can't short it by rule. If a stock is marginable then it is up to the broker/dealer and stock availability. Initial margin goes up to 100% for sub $5, but technically they are still marginable, therefore still shortable. As a practical matter, most broker/dealers won't allow shorts on sub $5 stocks.