Trading can only take place in the markets if the buyers are able to find sellers at a very low cost.
So there are basically four important questions about the trade that needs to be answered, in order to understand the mechanism of trade in a financial market. These four questions are:
1.1. When can trade occur?
The answer to this question is different for different markets and situations.
a. In a call market, the trade occurs only at particular times and places. All the bids and asks are balanced to determine one price, where the quantity bid is equal to the quantity offered. And all trades in such a market occur at this price. Many continuous trading markets find their opening price by this method. Thus, the call market is very liquid during the sessions and is illiquid otherwise.
b. In a continuous market, the trades can be arranged and executed anytime the market is open.
1.2. Who arranges the trade?
a. In a call market, the trades are arranged through an auction process. It is the buyers and the sellers, who through their collective bids determine the market prices.
b. In a continuous market, the trades can be arranged either through the auction or through the dealer’s bid-ask quotes (for example the stock exchange trades).
1.3. How are trades executed?
The trades are executed through three markets, discussed as follows:
a. Quote Driven Markets. These markets are also called price-driven or dealer’s markets. In such markets, the individual dealers ‘make a market’ in specific securities, i.e. they are willing to both buy and sell the securities. In such markets, both the customers and the dealers deal with the other dealers to make the trade-in bonds, stocks, and commodities. This market is also often referred to as an OTC or over-the-counter market.
b. Order Driven Markets. This is a pure auction market, where both the buyers and the sellers submit the bids and offer to the exchanges.
There is order matching rules in such markets, where the buy and sell orders are ranked based on:
i. The price precedence. This is the primary rule for setting the price. Here all the bids and asks are ranked, and the best bid and ask are set as the price.
ii. The display precedence. This is a secondary rule for setting the price. As per this rule, the display order has precedence over the hidden orders. This rule is applied when the primary rule gives more than one best-ranked price.
iii. The time precedence. This is also a secondary rule. As per this rule, the preference is given to the orders given first over the others with the same price and display properties.
c. Trade Pricing Rule. There are two kinds of rules for such pricing. They are:
i. Uniform Pricing Rule. As per this rule, the same price is used for all trades, used by the call markets.
ii. Discriminating Pricing Rule. As per this rule, the limit price of the order/quote that arrives first determines the trade price.
iii. Derivative Pricing Rule. This rule makes use of the mid-point of bid-ask prices from another market to determine the trade price.
d. Brokered Markets. These are the markets, where the brokers arrange the trades among their clients. These are usually very thin markets for the unique markets.
1.4. How do they learn about the price?
a. The traders learn about the prices from the pre-trade and post-trade information available in the market.
b. All the exchanges publish real-time data about the quotes and orders, this adds to the pre-trade transparency about the price information available.
c. In most of the dealer’s markets, there is a published data about the trade prices after the trades occur. This results in post-trade transparency about the price information. The post-trade transparency results in wider spreads for the dealers and higher transaction cost for the investors.