Two CFD instruments can display nearly identical price movements while producing very different financial results. Their contract sizes, trading increments, margin requirements and execution rules may differ substantially. For an automated strategy, interpreting these specifications correctly is as important as identifying a trading opportunity.
In mt5, MQL5 programs can retrieve instrument specifications through functions such as SymbolInfoDouble, SymbolInfoInteger and SymbolInfoString. These properties allow trading logic to adapt to different markets, but incorrect assumptions can introduce five distinct risks.
Contract Specifications Can Produce Incorrect Position Exposure
A program that calculates trade size from price distance alone may overlook how much underlying exposure each lot represents. The SYMBOL_TRADE_CONTRACT_SIZE property identifies the contract size, while the instrument’s calculation mode determines how that specification affects valuation.
A strategy developed for a currency pair cannot safely apply identical volume calculations to an equity index or agricultural commodity CFD.
The resulting error may remain hidden until a relatively small price movement generates an unexpectedly large account change. Examine contract size, calculation mode and expected profit using OrderCalcProfit before submitting an order.
Tick Size and Decimal Precision Can Generate Invalid Prices
Displayed decimal places do not necessarily determine the smallest permitted trading increment. SYMBOL_DIGITS describes quotation precision, while SYMBOL_TRADE_TICK_SIZE specifies the actual price increment used for trading.
A CFD might display prices to two decimal places but accept orders only in increments of 0.05. An algorithm submitting a stop at 72.43 could encounter rejection or require adjustment to a valid increment.
Price normalization must therefore follow the tick-size specification rather than merely rounding to the displayed number of decimals. Check accepted price increments whenever an application changes instruments.
Volume Steps Can Turn a Small Sizing Error Into Excessive Risk
Imagine a hypothetical palladium CFD quoted at $1,050 per ounce, with each lot representing 25 ounces. An algorithm calculates a desired exposure of 37.5 ounces, equivalent to 1.5 lots. However, the broker permits trading only in whole lots.
Rounding upward produces two lots, representing 50 ounces and $52,500 in notional exposure. If palladium declines to $1,020, the position loses $1,500 before charges. The intended 37.5-ounce exposure would have lost $1,125, making the rounding decision responsible for an additional $375 loss.
Rounding downward to one lot reduces exposure instead. Neither adjustment is economically neutral. MQL5 programs should inspect SYMBOL_VOLUME_MIN, SYMBOL_VOLUME_MAX and SYMBOL_VOLUME_STEP, then reject orders when permitted volume cannot satisfy the strategy’s risk limit.
Stop-Level Restrictions Can Prevent Protective Orders From Being Accepted
Broker-defined stop-distance requirements determine how close certain protective and pending orders may be placed to the current market. SYMBOL_TRADE_STOPS_LEVEL provides the minimum distance in points, while SYMBOL_TRADE_FREEZE_LEVEL identifies restrictions affecting certain modifications near market prices.
A strategy may calculate a technically valid stop from chart support but still submit an instruction that violates the instrument’s trading rules.
For mt5 automation, these properties should be checked against current bid and ask quotations before order submission. When spreads widen, a previously acceptable distance may become insufficient. The program must distinguish a rejected protective order from a successfully protected position.
Trading Permissions and Filling Rules Can Differ Between Instruments
Not every symbol permits the same order types, trading directions or execution policies. SYMBOL_TRADE_MODE indicates trading permissions, while SYMBOL_FILLING_MODE describes supported filling policies. Session restrictions can further limit when transactions are accepted.
An application that assumes every CFD supports its preferred filling method may fail precisely when rapid execution is needed. A successful strategy test on one instrument does not establish compatibility with another.
Before opening a CFD through an MQL5 program, retrieve the current symbol properties, validate volume and tick increments, calculate projected profit and margin, and use OrderCheck to examine the proposed request before sending it.