Flash PMI versus the final reading two weeks later: does the gap ever change your trade?

S&P Global publishes a "flash" PMI reading about a week before the "final" one for the same month. The flash is built from roughly 80–90% of the survey responses the final figure uses, and it's meant to be an accurate early read rather than a rough guess: for the US composite index, the average gap between flash and final has historically been small, around 0.1 to 0.4 points.

This month's flash readings were published on 23 September and made real news: the US composite hit a 62-month high at 58.4, the UK composite fell to a three-month low at 51.7, and the eurozone composite rose to 53.1 (full report). The final figures for all three come out in early October.

For newer members, this raises a genuinely practical question: does the flash number matter enough to trade, given a more complete number is coming soon after?

• Do you treat the flash reading as tradeable on its own, or do you wait for the final figure because the gap, even if usually small, isn't zero?
• Has a final PMI ever moved a currency meaningfully after the market had already reacted to the flash?
• If you do trade the flash, what do you do with the position by the time the final figure comes out?
• PMIs explained and ISM versus PMI: which do you trust for the US? cover the basics if you're catching up.

There's no wrong answer here; we're mainly interested in how members who've been through a few PMI cycles actually handle it. Please share your own experience. Posts that promise a direction or sell signals will be removed.