Organization and Functioning of Securities Markets

A well-functioning securities market will offer the following characteristics:

Timely and accurate information
Liquidity
Internal efficiency
Informational efficiency

市场分类：

一级市场：
组织 organization
风险承担 risk bearing
分配 distribution

二级市场：underwriter 承销
二级市场的繁荣，即流通顺畅，价格反应迅速，交易量增加，可以变相刺激一级市场的繁荣。

Call market & continuous market
In call market, the stock is traded at specific times; in continuous markets, trades occur at any time the market is open.

Primary listing markets are the exchanges that formally list a corporation's stock. (国家挂牌股票交易所)

New York Security Exchange (NYSE) lists more than 2700 firms and has an average daily volume of 1.5 billion shares.
The American Stock Exchange (AMEX) primarily lists stocks not traded on the NYSE, along with foreign shares, warrants, options, and exchange-traded funds (ETFs).
The Nasdaq National Market System (NMS) has traditionally been desrcribed as an over-the-counter (OTC) market.

Reginal exchange (地区股票交易所)
当地小公司股票在此交易。对挂牌上市的公司规模要求要低很多。如Chicago and Pacific stock exchanges.

Third market (柜台市场) = over-the counter market (又称柜台市场) 只要任何具有一定资格的交易商愿意充当某种证券的做市场，这种证券就可以在柜台市场上交易。

已在交易所公开挂牌上市的证券也可以在柜台市场进行交易，非交易所会员的投资公司可以作为证券的交易上而不通过交易所。

Alternative trading systems refer to computerized systems that do not formally list stocks. These include electronic communications networks that serve retail borkers and small institutional traders, and electronic crossing systems that match large buy and sell orders. these systems do not list stocks, but stocks that are listed on exchanges trade on the alternative systems. This is referred to as "fourth market" trading.

Membership on the U.S. Exchanges falls into 4 different categories.

Specialists 但当做市商
Commission brokers 佣金经纪人
Floor brokers 大堂经纪人：为其他经纪人交易，并收取费用。
Registered traders trade for their own accounts 自营商，为自己账户交易。

订单指令种类：
market orders 普通的市场股票交易买卖
limit orders 限量订单指令
short sale orders 保证金指令
stop loss orders 止损指令：如买时$10为了防止过度损失，规定$8平仓

做市商：（通俗点讲就一套利的仓库）
美国证券交易所的做市商成为专家(specialists)。当某种证券交易清淡，交易者少，可能一个买者要等待很久才能碰到一个卖者交易。做市商用来这种情况下增加市场的流动性，他同时报出买入价(bid price)和卖出价(ask price)以供投资者进行交易，用自己的账户从卖者处买入证券，将证券卖给买入者，从而提供流动性。做市商同时负责保存并处理该证券的限价指令。做市商的收入来源于买入价和卖出价的差额以及限价指令交易的佣金。

卖空是指股票投资者当某种股票价格看跌时，便从经纪人手中借入该股票抛出，在发生实际交割前，将卖出股票如数补进，交割时，只结清差价的投机行为。若日后该股票价格果然下落时，再从更低的价格买进股票归还经纪人，从而赚取中间差价。<转自百度>

Marginal transaction 保证金交易：用借的钱购买证券，经纪公司节前给客户，用所购买的证券做抵押。

trigger price = P0[(1- initial margin) / (1-maintenance margin)]