The 9:30 equity open and what it does to dollar pairs

[Shadow Trader]

At 9:30 Eastern, the US stock market opens. Volume floods in and volatility spikes in equity futures. Currency pairs, especially those sensitive to risk sentiment such as AUDUSD and USDJPY, often feel the impact.

The first ten minutes frequently bring sharp moves with no relation to currency news. Large equity orders cause flows in related markets, and algorithms trading across assets transmit the volatility.

A particular feature is the opening auction. Equity indices have an opening imbalance, which affects futures right at the open. Currency traders watching only FX charts see a surprise movement.

It's also a time when the dollar can reverse its earlier trend. A morning of dollar buying can turn on the stock open if equities rally strongly and risk assets get a bid.

Scalpers may have noticed a rise in spreads at 9:30 and a few minutes of whipsaw. It's another of those recurring moments that aren't on the economic calendar.

Keeping an equity index chart on a second screen lets the trader see whether the FX move comes from stocks. If so, it tends to fade as the stock market settles. If not, it may represent a currency-specific story.

How does your main pair behave in the first ten minutes after the US stock market opens?

[Amanhasnoname]

USDJPY is where I see this most clearly. For a long time I couldn't understand why my calm New York morning trades would suddenly get shaken out at half past nine with nothing on the calendar. Once I put an S&P futures chart next to it, the reason was obvious. The yen pair was simply following the stock open.

The first ten minutes are often the worst of the whole session for me. Spreads widen a little, price whips both ways, and then quite often it drifts back to where it was before the bell. On a couple of occasions a strong equity rally completely reversed a morning of dollar strength, which caught me out the first time.

My rule now is no new trades from about two minutes before the stock open until ten minutes after, unless the move in FX clearly isn't coming from equities. If the index is flat and the yen still moves, it's probably a currency story and worth looking at.