构成商品交易的一个基本前提是供需双方的共同存在,而市场经济的建立,则是为供需双方的交易建立规则和提供平台。在这里,买和卖同样重要,发扬契约精神、维护双方的合法利益是市场经济的前提。在证券市场上,人们习惯以多空来代表参与交易的两方,看多者在操作行为上是买入,看空者则是卖出。由于证券交易具有流动性强、价格变化快的特点,在实践中,买卖双方的角色经常在变换,在高频交易中甚至随时都在变化。因此,理论上说,股市中没有绝 A basic prerequisite for the formation of commodity transactions is the coexistence of both supply and demand parties. The establishment of a market economy is to establish rules and provide a platform for the transaction between supply and demand parties. Here, buying and selling are just as important as preconditions for a market economy to carry forward the spirit of the contract and safeguard the legitimate interests of both parties. In the securities market, people are accustomed to long and short to represent the two sides involved in the transaction, to see more people in the operating behavior is to buy, the bear is sold. Due to the characteristics of liquidity and rapid price changes in securities trading, in practice, the roles of buyers and sellers often change, and even change frequently in high-frequency trading. Therefore, in theory, there is no absolute stock market