AUD/USD's largest one-day move of September 2026

AUD/USD's largest one-day move of September 2026, to 28 September, was a rise of 0.64% at the ECB fixing of 3 September. That figure is our own calculation from European Central Bank reference rates, which are set for information purposes, so it is worth checking against the published rate before relying on it for anything.

Why the percentage alone is not enough

A 0.64% move means something different depending on how AUD/USD usually behaves. The same shift in a pair that rarely moves is a bigger event than it is in one that moves that much most weeks. To read it properly, the move needs to be set against the pair's typical day, which we define as the standard deviation of its daily changes over the previous 20 ECB fixings, expressed in pips.

Stating a move as a multiple of that typical day is what turns a raw number into something comparable from one day to the next, and from one pair to another.

AUD/USD's largest one-day move of September 2026, to the 28th, was a rise of 0.64% at the ECB fixing of 3 September. That figure is our own calculation from European Central Bank reference rates, so it could contain errors and it is already out of date.

Where the rise sits against the rest of the month

Of the fixings measured through September, none moved the pair by a larger margin in either direction than 3 September did. The gain did not hold. By the ECB fixing of 28 September, AUD/USD had fallen 1.59% against the US dollar from the fixing of 21 September, the largest fall of the six major pairs measured against the dollar over that stretch. A five-day cumulative fall and a single day's rise are different kinds of move, so the two figures are not directly comparable, but together they show an early gain that gave way to a sustained decline by the close of the month.

No sourced event recorded for 3 September

No dated release or statement from an official source, such as the Reserve Bank of Australia or a scheduled statistical publisher, is logged against 3 September 2026 for this pair. The events calendar and the central banks hub carry no entry for that date, and the economic data hub shows nothing released on it that is tied to the Australian dollar. A move without a named release behind it is not unusual. It simply means the cause has not been traced to a single dated source, and none is attributed here until one is found.

Sources

The rate used to identify the largest one-day move is the ECB reference rate, set at approximately 14:10 CET and published at approximately 16:00 CET for information purposes only, not as a dealing price. The percentage change, the pip count and the normal-day multiple shown on this page are our calculation from ECB reference rates. Where an event is named as scheduled or published on the date of the move, it carries its own source and timestamp alongside it. Where no sourced event is registered against a date, the page says so.

What would change our view

• A sourced event, statement or release timestamped to 3 September 2026 that is later added to an official calendar and can be matched to the move.
• A revision to the ECB reference rate for the dates used in this calculation, which would change the pip count, the percentage and the normal-day multiple together.
• A later daily move in September 2026 that exceeds 0.64% would replace this finding.

Any of these would prompt a correction to the figures above.

Corrections

No corrections to this piece. Last checked against ECB reference rates to 28 September 2026.