In economics, market clearing is the process by which, in an economic market, the supply of whatever is traded is equated to the demand so that there is no excess supply or demand. The new classical economics assumes that in any given market, assuming that all buyers and sellers have access to information and that there is no "friction" impeding price changes, prices always adjust up or down to ensure market clearing. Mechanism and examples A market-clearing price is the price of a good or service at which quantity supplied is equal to quantity demanded, also called the equilibrium price. The theory claims that markets tend to move toward this price. For a one-time sale of goods, supply is fixed, so the market-clearing price is simply the maximum price at which all items can be sold. For a market where goods are produced and sold on an ongoing basis, the theory predicts that the market will move toward a price where the quantity supplied in a broad time period will equal the quantity demanded. This might be measured over a period like a week, month, or year to smooth out irregularities caused by manufacturing in batches and delivery schedules; sellers often have a buffer of inventory so that products are always available for retail sale. The market is cleared when the price brings demand and supply into balance, allowing anyone to purchase or sell whatever they want at that price. A market clearing occurs when supply and demand are equal. By definition, there must be a shortage or surplus if the market does not clear. A shortage refers to buyers wanting to acquire something but being unable to do so at current prices, while a surplus refers to excess product beyond the amount that buyers will acquire at current prices. New classical economics does not assume perfect information in the short-run, but markets may approach efficient outcomes as information is discovered. If the sale price is higher than the market-clearing price, then supply will exceed demand, and a surplus inventory will build up over the long run. If the sale price is lower than the market-clearing price, then demand will exceed supply, and in the long run, shortages will result, where buyers sometimes find no products for sale at any price. The first version of the market-clearing theory assumes that the price adjustment process occurs instantaneously. For example, if a