The first trading day of the month has its own personality
Posted: Sat Oct 31, 2026 6:50 pm
At the start of a new month, new allocations, fresh risk budgets, and a flood of data releases arrive together. Manufacturing PMIs land on the first business day, and employment data often follows within days.
Behavior on those days can differ from the rest of the month. Some traders report a calm morning followed by sharp afternoon moves, others observe a tendency for trends that began in the prior month to pause.
Participation may also be different. Portfolio managers adjust positions, and flows linked to month-start funding can influence short-term currency movements.
A test is straightforward: tag every day by its position in the month, and compare performance metrics for the first and second days against the rest. With sufficient history, any difference becomes visible, though with 12 observations per year, sample size is limited and caution is needed.
If a difference appears, the adjustment can be modest, such as smaller size or a narrower time window on those days.
Does the strategy's performance differ on the first trading day of the month?
Behavior on those days can differ from the rest of the month. Some traders report a calm morning followed by sharp afternoon moves, others observe a tendency for trends that began in the prior month to pause.
Participation may also be different. Portfolio managers adjust positions, and flows linked to month-start funding can influence short-term currency movements.
A test is straightforward: tag every day by its position in the month, and compare performance metrics for the first and second days against the rest. With sufficient history, any difference becomes visible, though with 12 observations per year, sample size is limited and caution is needed.
If a difference appears, the adjustment can be modest, such as smaller size or a narrower time window on those days.
Does the strategy's performance differ on the first trading day of the month?