The functionality of the Spread Controller has now been replaced by built-in functionality in MT4's own strategy tester. This app is now redundant, and is provided only for legacy use on v482 of MT4 and earlier.

MT4's strategy tester uses the current live spread at the time a test is started. There are two serious problems with this approach:

• Test results can vary significantly depending on the live spread when the test is started. Consecutive tests of the same strategy may yield very different results.
• The results can be very optimistic if the strategy is spread-sensitive, and the live spread is below average at the time the test is started.

Version 2 of the Spread Controller offers simple, quick control over the spread used in each backtest. You turn on the Spread Controller by running a script (on any chart) when you start MT4. After that, whenever you run a backtest you will be prompted to change the spread which is about to be used.

In the new version of the Spread Controller there is no longer a need to restart MT4 after each change of spread, and no need to disconnect MT4 from the broker. All you have to do is run one script, and then enter the spread figure which you want to use at the start of each backtest.