Dollar slips before US CPI as Williams cools hike bets: what CPI means

The US dollar fell against every major currency on Tuesday, FXStreet reports, after New York Fed President John Williams said he sees no rate hike in 2027, according to FXStreet. Traders now wait for Wednesday's US inflation report, the September Consumer Price Index (CPI).

The ECB reference rates from the 13 October fixing show the same direction. NZD/USD rose 0.25% to 0.5613, USD/CAD fell 0.15% to 1.4241 and EUR/USD edged up 0.06% to 1.1188. These are official once-a-day fixings, not live quotes. Not every Fed voice agrees with Williams: Boston Fed President Susan Collins repeated her support for another hike before year-end, investingLive reports. That split is why CPI matters so much this week.

What is the Consumer Price Index (CPI)?

CPI measures how much the prices of everyday goods and services change over time. Think of a basket of food, fuel, rent and services. If the basket costs more than before, prices are rising. That is inflation.

There are two main versions:

• Headline CPI includes everything, including energy and food, which can jump around.
• Core CPI removes energy and food. Central banks watch it to see whether price pressure is spreading across the economy.

Why do currency traders care? A central bank such as the Federal Reserve (the Fed) raises interest rates to fight inflation. Higher rates tend to attract money into a currency. So a hot CPI reading can lift the dollar, and a soft one can weigh on it.

A worked example

Step 1: the forecast. According to investingLive, 14 investment bank forecasters see energy lifting headline inflation to 3.6%, with monthly core held near 0.2%. A separate investingLive preview puts expected headline CPI at +0.6% month over month. The report is due at 8:30 AM ET.

Step 2: the surprise. Markets react to the gap between the actual number and the forecast, not to the number alone. investingLive says the headline jump is largely priced in, so core decides the reaction. Its scenarios:

• A core print of about 0.24% or higher: 0.24 minus 0.20 = a surprise of +0.04 percentage points. investingLive says this would firm December hike pricing and lift the dollar.
• A core print of 0.16% to 0.18%: 0.18 minus 0.20 = a surprise of -0.02 points, or more. investingLive says this would support Williams' view.

Step 3: measuring a currency move. Here is how the NZD/USD fixing change is calculated:

• New fixing minus old: 0.5613 minus 0.5599 = 0.0014
• Divide by the old fixing: 0.0014 / 0.5599 = 0.0025
• Multiply by 100: 0.25%

You can use the same steps on Wednesday's move after the data. Track the pair on a NZD/USD chart or the US Dollar Index chart.

Why it matters for new traders

CPI day is one of the busiest days in the forex calendar. Prices can move fast in the minutes after the release. Spreads, the gap between buying and selling prices, can widen too.

The moves before the data also tell a story. FXStreet says the Aussie gained over 0.34% on Tuesday as Williams pushed the brakes on rates. Meanwhile, FXStreet reports gold drifted to near $4,155 as rising oil prices fuelled inflation concerns. Inflation worries show up in many markets at once.

Remember that a number is only "hot" or "soft" compared with what was expected. For a wider look at Tuesday's session, see our sister site's report on the dollar falling across majors as Williams cooled hike bets.

Key terms

• CPI: a measure of changes in consumer prices.
• Headline CPI: the full measure, including energy and food.
• Core CPI: CPI without energy and food.
• Surprise: the actual reading minus the forecast.
• Priced in: already reflected in market prices before the data arrives.
• Fixing: an official reference rate set once per business day, not a live quote.