PNI. On large orders to buy or sell, an instruction given to a broker from institutional buyers or sellers not to initiate a new price, but either to let the market create a new price or obtain a favorable price through gradual and intermittent transactions. This allows the buyers or sellers to accumulate or distribute shares without disturbing the market forces. This could also be done by institutions that are not permitted by law to create an uptick or a downtick in the market.