Market-on-Open Order

Market-on-open (MOO) in stock-market context means an order that executes at the opening auction price — typically the official 'open' print used to start the day's regular trading. The forex market has no equivalent opening auction because trading is continuous 24/5; the closest analogue is timing market orders to specific session opens.

Forex session-open conventions: - London open: 08:00 GMT (07:00 BST during summer) - NY open: 14:00 GMT (13:00 BST during summer) - Tokyo open: 00:00 GMT (typically 23:00 GMT on Sunday for the new trading week's start) - Wellington open: 22:00 GMT (effectively the trading week's start)

EA implementations of session-open entries: 1. Time check: the EA checks current server time against the configured session open. The server-time vs UTC offset varies by broker — IC Markets uses GMT+2/+3 depending on DST; FXOpen uses GMT; OANDA uses ET. EA must account for these to time entries correctly. 2. Session window: typical implementations open positions in a brief window after session open (first 5-60 minutes). Configurable as `OpenSessionAfterMinutes` (when to start considering entries) and `OpenSessionUntilMinutes` (when to stop). 3. Range definition: many session-open strategies require a pre-defined range (e.g. Asian session high/low) that the EA tracks before placing the breakout order. Implementation requires storing the range during pre-session and using it for entry conditions at open.

Common session-open strategy patterns:

1. London Open Breakout: track the Asian session range (typically 22:00-08:00 GMT). At London open, place buy-stop above the Asian high and sell-stop below the Asian low. First breakout triggers entry; the other is cancelled (OCO pattern).

2. London Range Continuation: at London open, identify trend direction from H4 chart. Place market order in trend direction with stop at recent swing.

3. NY Open USD-pair Fade: trade against the London-session move at NY open, anticipating mean-reversion. Higher-risk pattern; works in specific regimes.

Implementation considerations: - DST transitions: spring/fall DST changes shift the session-open times relative to UTC; the EA must handle these to avoid missing or duplicating entries - Spread spike: many brokers widen spreads briefly around session opens; the EA should validate spread is within acceptable bounds before entering - Liquidity: session-open trades may see partial fills or off-quote rejections if entered exactly at the open moment; small delay (e.g. 30-90 seconds after open) often produces cleaner fills - Holiday handling: bank holidays in the UK affect London-open behaviour; the EA should optionally skip trading on configured holidays

For scalping EAs: session-open trading is one of the cleaner opportunities because liquidity is reliable and direction often persists for 1-3 hours. Breakopedia and similar London-session EAs target this regime.