Forex glossary
Session Overlap
Session overlap is the part of the day when two regional FX centres' activity hours coincide, such as London and New York. Liquidity or volatility may increase but depend on the pair and events. The UTC window shifts with local daylight-saving rules; OTC sessions have no single official universal schedule.
Illustrative example
How does it work in practice?
Assume two illustrative activity windows in UTC: 08:00–17:00 and 13:00–22:00. Their overlap is 13:00–17:00, lasting four hours; if the time-zone offsets change, the overlap must be recalculated.
A case to work through
The shared interval
Fictional UTC windows are 07:00–16:00 and 12:00–21:00.
- The overlap starts at the later start, 12:00.
- It ends at the earlier finish, 16:00, lasting four hours.
What follows? Recalculate both windows after offset changes.
Example boundary: These are illustrative windows rather than official hours for all FX.
A useful distinction
Session Overlap / Forex Liquidity
Liquidity describes execution conditions; overlap describes shared activity timing.
Check your understanding
Find two hypothetical windows' intersection.
Show the answer and explanation
14–15
Both windows include that hour.
Sessions, time zones and breaks
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Read the fuller explanation
Related terms
Sources and documentation
- When do the clocks change? – GOV.UK
Confirms UK offset changes between GMT and BST.
Document read: - Daylight Saving Time Rules – NIST
Confirms US daylight-saving rules differing from the UK's.
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.