Peso and Aussie slip as US yields surge: what risk-on and risk-off mean

The Mexican peso gave back its gains at Wednesday's ECB fixing. The USD/MXN reference rate for 7 October rose 0.83% to 18.094, from 17.945 a day earlier, as a jump in US Treasury yields soured the mood across markets. Our last lesson used the peso's rise to explain the carry trade. One fixing later, the move has reversed.

FXStreet reports that the US 10-year yield touched 5.35% and the 30-year reached 5.724%, both 24-year highs. investingLive's European session wrap described stocks sliding "as risk mood sours". The Australian and New Zealand dollars also fell against the US dollar at the fixing. Our sister site has more on the US yield spike and the weaker EUR/USD fixing.

What is risk-on and risk-off?

Risk-on and risk-off are shorthand for the mood of investors.

• In a risk-on mood, investors feel confident. They buy assets that can pay more but can also fall harder, such as shares and currencies of countries with higher interest rates. The Mexican peso and the Australian dollar are common examples.
• In a risk-off mood, investors get nervous. They sell those riskier assets and move money into things they see as safer.

Currencies often move in groups because of this. When the mood turns risk-off, the riskier currencies tend to fall together. That is why traders watch stocks, bond yields and oil, not just one currency pair.

The pattern is not a fixed rule. On Wednesday the Japanese yen and Swiss franc, often seen as safe places, also weakened slightly against the US dollar. The dollar itself was the main winner. FXStreet notes the US Dollar Index climbed back near an 18-month high as yields rose.

A worked example

Here are the ECB fixings for 6 and 7 October. The change is the new rate minus the old rate, divided by the old rate.

Take USD/MXN. 18.094 minus 17.945 equals 0.149. Then 0.149 divided by 17.945 equals about 0.0083, or 0.83%. A higher USD/MXN means one dollar buys more pesos, so the peso got weaker.

For AUD/USD, 0.6951 minus 0.6982 equals -0.0031. Then -0.0031 divided by 0.6982 is about -0.44%. A lower AUD/USD means the Australian dollar got weaker.

Now a simple money example. Say someone swapped $10,000 into pesos at the 6 October fixing: 10,000 × 17.945 = 179,450 pesos. Swapping back at the 7 October fixing gives 179,450 ÷ 18.094 = about $9,917.65. That is a drop of roughly $82 in one day, before any costs. Remember these are once-a-day reference rates, not prices you could trade at.

FXStreet also reports that AUD/USD fell 0.44% on Wednesday, snapping a three-day winning streak. You can follow the pairs on USD/MXN and AUD/USD charts.

Why it matters for new traders

• Positions can be linked. Holding both pesos and Australian dollars can feel like two separate ideas. In a risk-off day they may lose together.
• The driver may sit outside forex. Wednesday's trigger came from the bond market, not from Mexico or Australia.
• Moods flip fast. The peso rose 1.13% one fixing earlier, then fell back. A strategy that works in a calm market can suffer when sentiment turns.
• Exceptions happen. The yen and franc did not gain against the dollar this time. Check the data rather than assuming a textbook reaction.

Key terms

• Risk-on: a confident market mood where investors buy riskier assets.
• Risk-off: a nervous mood where investors sell riskier assets and seek safety.
• Treasury yield: the return investors earn on US government bonds. Higher yields can pull money toward the dollar.
• Reference rate (fixing): an official exchange rate the ECB publishes once per business day. It is not a live quote.
• Risk-sensitive currency: a currency, such as the peso or Australian dollar, that tends to rise and fall with investor confidence.