Market Microstructure
Order – specifies what to trade, how much, buy or sell, and conditions
Orders are made because traders do not usually arrange their own trades – go through a broker or dealer
Market liquidity – degree to which traders can trade without affecting prices
Offering or supplying liquidity (posting bid and ask quotes) – gives other traders an opportunity to trade
Dealers make money by selling liquidity – posting bid and ask quotes
Standing order = open order → an open offer to trade
Taking liquidity – accepting an offer to trade
Market order – trade at the best price currently available in the market
Fills quickly, but perhaps at an inferior price
Market orders take liquidity from the market
Transaction cost = ½ the spread
Price Improvement – trader steps in front of best bid or ask to take an incoming market order
Market Impact – traders move prices in order to fill their orders – the most significant cost of trading large orders
Limit Orders – trade at the best price available, but only if it is no worse than the limit price.
Limit Buy – trade at or below limit price
Limit Sell – trade at or above limit price
Marketable limit order – can be executed immediately
Standing limit orders are free options – but, unlike regular options, they can be cancelled by the writer at any time
Sell limit orders are calls
Buy limit orders are puts
Strike is the limit price
Option value depends on the limit price and the volatility
Since bid and ask are limit orders (options), and options are worth more in volatile markets, spreads tend to be wider as volatility increases
Compensation for offering liquidity – expect better prices than with market orders
You make money on the spread with a limit order, but the spread costs you money with a market order
Stop orders – buy only after price rises to the stop price or sell only after price falls to the stop price
Stop-loss orders are the most common
No guarantee sale will be at your specified price if price drops through it
Stop orders accelerate price changes
Markets
Continuous Markets – arrange trades whenever the market is open
Call Markets – trade only when the market is called
Primary mkt for Treasuries is an example
NYSE starts as call but switches to continuous each day
Execution Systems
Quote driven with dealers = Dealer markets – dealers arrange trades and trade with customers. Public traders don’t trade with each other.
Nasdaq is example
Interdealer brokers may help dealers arrange trades among themselves – offer anonymity.
Order driven – buyers and sellers are matched by order precedence and trading price rules
They trade directly – without dealers
Traders offer or take liquidity
Hybrid markets – NYSE is order driven, but specialists will offer liquidity if needed
Order Precedence Rules – which buyers match with which sellers?
Trading Price Rules – once matched – at what price do they trade?
Minimum price increase – tick size
Transparency – degree and speed with which quotes and orders are made public
Stock markets are more transparent than bond markets
Oral Auctions
Example: U.S. Gov. T-bond Futures on CBT
500+ floor traders
bids and offers are called out
“take it” to accept offer
“sold” to accept bid
take turns bidding and offering as negotiating
All bids and offers must be public
First trader to accept gets to trade
Acceptances must be expressed publicly
Order precedence Rules
Primary – price priority
Secondary – usually time priority
Price priority – precedence to traders who bid and offer the best prices (the inside spread) Taders cannot accept bids or offers at any inferior price.
Can only bid or offer with price improvement
Time precedence – precedence to the traders whose bid or offer first improves the current best bid or offer
After a bid or offer is accepted or withdrawn, anyone may bid or offer at a new price
Traders who want to trade ahead of a trader who has time precedence must improve the price – this rewards aggressive pricing
But you must improve by at least the minimum price increment
This can involve some strategy
Discriminatory Pricing – used in oral auctions – every trade takes place at the price proposed by the trader whose bid or offer is accepted.
Single Price Auction = Uniform Pricing – all trades take place at the same market-clearing price.
The last match that leads to a trade determines the clearing price
Used with Treasury auctions
Clears where supply meets demand
Continuous markets use discriminating pricing
Call markets can use discriminating pricing or uniform pricing
Continuous rule-based order matching system with discriminatory pricing:
Order book is kept
When new order arrives – matching system attempts to trade with the order on the opposite side with the highest precedence
If new order can’t trade immediately, it is placed in the order book according to precedence
The limit price of the standing order determines the price for each trade
If an incoming order is large, it may be matched with several standing limit orders – at each of their prices
Large impatient traders prefer discriminatory pricing rule over uniform pricing rule. It allows them to trade the first parts of their orders at better prices than the latter parts.
Standing limit orders prefer uniform pricing rule so that large traders can’t discriminate among them.
Limit order traders tend to issue more aggressively priced orders under uniform pricing than discriminatory pricing
1