Why news events hit EA strategies particularly hard
Under normal market conditions your EA trades statistical patterns that have worked historically: spreads stay within expected ranges, price movements have a degree of continuity, and slippage remains manageable.
During a high-impact economic release like the US Non-Farm Payrolls or a surprise FOMC decision, this changes abruptly:
- Spread explosion: Many brokers widen the spread from 1–2 pips to 10–50+ pips in the seconds before and after the release.
- Slippage: Market orders are executed at prices significantly worse than the EA calculated. With 30 pips of slippage, a 15-pip stop-loss is instantly irrelevant.
- Flash moves: Prices can move 100+ pips in milliseconds, skip over stop-loss orders, then reverse — the trade is closed at a loss even though the move was not sustained.
- Requotes: On servers under heavy load, orders are rejected or filled at completely different prices.
A scalping EA with a 5-pip stop can lose its entire daily profit potential in a single news trade during these moments.
What a news filter does
A news filter stops the EA from trading for a configurable time window before and after defined scheduled releases — typically 30–60 minutes before and 30–60 minutes after publication.
Depending on the implementation it:
- Prevents opening new positions
- Closes all open positions shortly before the news
- Does both simultaneously
Not all filter implementations offer all three options. Closing open positions is more aggressive, but often necessary for tightly stopped systems — an open trade with a 5-pip stop rarely survives an NFP moment.
Implementation approaches in MT4/MT5
Approach 1: Built-in calendar check in the EA
Many commercial EAs contain an integrated news filter that queries an external economic calendar. The most widely used sources:
ForexFactory calendar (FF news filter): The de-facto standard in the MQL community. A free MQL4/MQL5 news filter calls the ForexFactory XML API and checks before every trade whether a high-impact event falls within the defined time window. Downside: ForexFactory can change or block the endpoint at any time.
Investing.com Economic Calendar: An alternative, also retrievable via HTTP request in the EA. More stable infrastructure, but slightly more complex integration.
Manually maintained dates file: The EA reads a local CSV file containing upcoming event times. No API dependency, but requires manual data maintenance.
Approach 2: External news-filter tool (overlay)
A separate EA or wrapper monitors all running EAs on the VPS and halts them during defined events. Advantage: a single filter for all EAs at once. This is particularly practical for multi-EA portfolios.
Approach 3: Broker-side pauses
Some brokers offer account settings that automatically restrict trading during certain news periods. This is rarely reliable enough for autonomous EA systems.
Configuration parameters: what you need to know
Most news filters have these parameters:
| Parameter | Typical value | Explanation |
|---|---|---|
NewsMinutesBefore | 30–60 | Minutes before publication during which no new trades are opened |
NewsMinutesAfter | 30–60 | Minutes after publication before the EA resumes trading |
NewsImpact | High | Which impact levels are considered (High/Medium/Low) |
CloseOnNews | true/false | Close open positions before the news? |
NewsPairs | EURUSD,GBPUSD | Filter only for specific pairs? |
Recommendation: Start with "High impact only" and 30/30 minutes. Extend to medium impact only after you have analysed whether those events actually disrupt your strategy.
The most important recurring high-impact events
For USD pairs:
- Non-Farm Payrolls (NFP): First Friday of the month, 08:30 ET
- FOMC rate decision: Approximately every 6–8 weeks, 14:00 ET
- US CPI: Monthly, 08:30 ET
- US GDP: Quarterly, 08:30 ET
For EUR pairs:
- ECB rate decision + press conference: Approximately every 6 weeks, 08:15/08:45 ET
- Eurozone CPI: Monthly
For GBP pairs:
- Bank of England MPC meeting: Approximately every 6 weeks
- UK CPI, GDP
Your EA only needs to filter events relevant to its traded instruments. An EA running on EURUSD does not need a filter for Australian rate decisions.
News filters and prop firms
Many prop firms have explicit rules against news trading — in particular against holding open positions through high-impact data releases. A missing news filter can trigger a challenge violation, even if no trade was opened during the news, but merely held.
Check your prop firm's rules carefully: is only trading during news prohibited, or also holding open positions? The latter requires a more aggressive filter configuration with CloseOnNews = true. More on this in the guide on passing a prop-firm challenge with an EA.
Impact on backtest quality
A critical point: many backtesting environments do not correctly simulate news events. The MT5 Strategy Tester does not replicate spread explosions or slippage spikes during data releases.
This means: an EA without a news filter looks better in backtesting than it will in live trading. When you activate the filter on the live EA, performance can either fall — because you miss profitable breakout trades — or improve — because you avoid devastating losses. Only a sufficiently long forward test reveals the true impact.
For more on rigorous backtesting and forward-testing methodology, see our dedicated guide.
Conclusion
A news filter is, for most EAs, not an optional extra but part of a complete risk management system. Scalpers, mean-reversion systems, and grid EAs can accumulate a week's worth of losses in a single poorly filtered news event. The technical implementation is straightforward — a ForexFactory-based filter can be integrated in a few hours. Combined with correctly configured position sizing and a reliable VPS, the major operational risk factors for an EA are under control. Our broker reviews indicate which providers maintain acceptable spreads during news windows.