The National Market System (NMS) promotes free market transparency by regulating how all major exchanges disclose and execute trades. To facilitate the fair distribution of information, the NMS requires that exchanges make bids and offers available and visible to both individual and institutional investors.The NMS also regulates short-selling, which is when an investor sells a security they do not own in hopes of buying it back at a lower price so they can profit from the difference. This ensures that markets are not manipulated by individuals with unfair advantages. Finally, the NMS protects investors from fraud by ensuring that all trades are executed fairly and transparently.