Market makers stand ready to buy and sell a particular stock on a regular and continuous basis at a publicly quoted price (bid and ask). In order to facilitate customer orders without delay, they are allowed to sell more than they have in inventory but they then buy to replace a short position on the same day or the next. This is called making a market.
MMs make money on the spread between the bid and ask and do NOT use shorting to manipulate stock prices. Market manipulation is illegal.
The bi-weekly short position data published by FINRA shows the aggregate short position on the 15th of the month and on the last trading day of the month. http://www.otcmarkets.com/stock/RFMK/short-sales
Anyone who would like more information on the short data reported by FINRA should call the Legal Section, Market Regulation at (240) 386-5126, or Office of General Counsel at (202) 728-8071.