Forex glossary
London Session
The London session is a conventional label for the FX trading-day window associated with activity in London's financial centre. OTC FX does not open with one exchange bell. Overlapping New York hours may increase activity, but liquidity and volatility depend on the pair and events; time conversions must account for daylight saving.
Illustrative example
How does it work in practice?
Suppose a London event is scheduled for 16:00 local time. In winter that is 16:00 UTC; under British Summer Time it is 15:00 UTC. A UTC-based chart therefore requires checking the date.
A case to work through
One local time, two offsets
A fictional event is at 10:00 London time; consider a GMT day and a BST day.
- Under GMT, it is 10:00 UTC.
- Under BST, subtract one hour: 09:00 UTC.
What follows? Label date and local time before comparing charts.
Example boundary: This does not define official hours for the entire OTC market.
A useful distinction
London Session / London Fix (4PM Fix)
The London fix has specified benchmark timing; the session is a broader activity window.
Check your understanding
Convert an illustrative London event into UTC.
Show the answer and explanation
09:00 UTC
BST is one hour ahead of UTC.
Sessions, time zones and breaks
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Related terms
Sources and documentation
- Triennial Central Bank Survey of foreign exchange and OTC derivatives markets in 2025 – BIS
Provides the earlier basis for distinguishing market participants and functions.
- When do the clocks change? – GOV.UK
Confirms UK offset changes between GMT and BST.
Document read: - The FX trade execution landscape through the prism of the 2025 BIS Triennial Survey
Describes fragmented FX execution, dealers, non-bank providers and internalised flows.
Document read:
The example illustrates the mechanism. Check current account conditions and instrument specifications with the provider.