Trading currency futures: contracts, rates and covered interest parity

A currency future is not a currency. It is a contract with a start date, an expiry, and a price that already has the difference between two interest rates built into it before anyone trades it.

Lesson 9 of 12. Every figure on this page is his, including the ones that show where his own model stops working.

Ten rules before the first contract

He opens the section with a list rather than a theory, and it is worth keeping in his order because rule five is the previous eight lessons compressed into a line.

  • Understanding market trends — analyse trends and patterns before making trades.
  • Leverage management — use leverage wisely to avoid significant losses.
  • Risk management — set stop-loss and take-profit levels for each trade.
  • Fundamental analysis — consider economic indicators, interest rates and geopolitical events.
  • Technical analysis — apply what you have learned from volume-based technical analysis, and avoid using lagging indicators.
  • Liquidity awareness — trade during high liquidity times for better price execution.
  • Volatility consideration — be prepared for price fluctuations and plan accordingly.
  • Stay informed — follow market news and updates and adapt your strategies.
  • Emotional control — avoid impulsive decisions and stick to your trading plan.
  • Choose reliable platforms — use trusted platforms with low fees and accurate market data.
His ten basic rules for trading currency pairs in futures, grouped into what to know, what to control and where to trade
Ten rules, and the fifth one points straight back at the rest of the course. Click to enlarge

What a currency future is priced off

Futures contracts for currency pairs are derived from the spot forex rates and used for risk management or for speculation. What moves the contract away from the spot rate is the interest rate differential between the base currency — all currency pairs against the US dollar — and the quote currency, the dollar. The difference in rates is what determines the price of the contract.

The benchmark behind those rates has changed, and he is precise about the relationship. LIBOR, the three-month interbank offered rate, served as the primary benchmark for short-term rates. Futures contracts were never directly based on it — but it influenced their pricing indirectly, by affecting the interest rates of the underlying currencies.

That benchmark has been replaced. SOFR — the Secured Overnight Financing Rate — in the United States, and ESTR, the Euro Short-Term Rate, in the eurozone. Direct reliance on LIBOR has diminished, and these are now the primary basis for determining rates and the differentials between currencies.

There is a mechanism under all of this worth understanding. When banks hold capital as short-term deposits — three months, say — the rate on that deposit affects the time value of money. Those deposits fund interbank lending, borrowing and FX swap transactions, and the FX swap is the fundamental basis of many currency futures contracts. So when banks outside the United States manage dollar deposits, the rates on them feed directly into the settlement rates of the contracts.

A futures price derived from the spot rate and shifted by the interest rate differential between the two currencies, with the benchmark rates that set it
Spot, plus the difference between two interest rates. The benchmark changed; the mechanism did not. Click to enlarge

The yield curve, and what it says about the differential

If the differential prices the contract, then anything that forecasts the differential forecasts the contract. That is what the yield curve is for here — it shows interest rates across different maturities, so it carries the market's view of where rates are going.

How he uses it:

  • A flat or inverted curve may indicate lower future interest rates, which affects the price of the pairs tied to those rates.
  • The shape itself is the signal — steepening or inverting. If the US dollar curve steepens, it could signal potential strengthening of the dollar against other currencies.
  • For a carry trade, the curve is how you judge whether a currency's yield will stay high. The trade lives on the differential persisting, and the curve is where you look to see whether it will.
  • For hedging, it lets you forecast future rates and use futures contracts against a possible change in them.
  • And a curve in negative territory reads as higher risk or a lack of confidence in growth, which may weaken the currency against others.
A steepening curve, a flat one and an inverted one, with what each implies for the currency and for a carry trade
Three shapes, three forecasts of the differential — which is three forecasts of the contract price. Click to enlarge

Reading the symbol

Before any of the theory, the practical part. A futures contract has a duration and an expiry, and the symbol tells you both.

Contracts typically run three months, equivalent to 91 days, with the expiration date usually falling on the third Friday of the expiration month — though he notes the date may vary on some platforms.

His worked example: a contract labelled 09-24 represents the third quarter of the year, starting on Friday, June 14, 2024 and ending on the third Friday of September 2024. On some platforms it is displayed as 6EU4. The new contract begins as the previous one ends — the 12-24 contract, shown as 6EZ4.

Which decodes as: 6E for the euro, Z for December, 4 for 2024. The month codes and the instrument codes are both worth having to hand:

  • Months — F January, G February, H March, J April, K May, M June, N July, Q August, U September, V October, X November, Z December.
  • Currencies — 6E Euro, 6A Australian Dollar, 6B British Pound, 6C Canadian Dollar, 6J Japanese Yen, 6S Swiss Franc, 6M Mexican Peso.
  • Indices and commodities — NQ Nasdaq-100, YM Dow Jones Industrial Average E-Mini, ES S&P 500 E-Mini, CL Crude Oil, GC Gold, SI Silver.
The four characters of a futures symbol taken apart, with the month codes and the quarterly contract cycle
Four characters, and each one is a fact. Instrument, month, year — and 91 days to the third Friday. Click to enlarge

The carry trade, and the trap underneath it

When the interest rate of one currency in a pair is lower than the other, carry traders act on it: selling the currency with the lower interest rate and buying the one with the higher rate. The logic is obvious, which is exactly the problem.

His observation, kept as he puts it: banks use this principle to trap these traders. Everyone can see the differential, so everyone is on the same side of it — and a crowded position at a level everybody knows is the setup from lesson six, arriving here through interest rates instead of through a chart.

Which is why the rest of this page exists. Understanding covered interest parity is what tells you where the fair price of that trade actually is.

A carry trader selling the low-rate currency and buying the high-rate one, and the reason the position can still go the wrong way
The obvious trade — and the reason it being obvious is the danger rather than the edge. Click to enlarge

Covered interest parity

He introduces it with both halves of the truth at once. Covered interest parity is sometimes described as a "law of physics" in international finance — and after the Global Financial Crisis of 2008 this principle no longer holds universally. The second half is why the chart section further down exists.

What it is for: determining the fair price of an FX swap or a forward contract, which are the fundamental tools for managing currency risk.

How an FX swap hedges that risk, in his example. Say you plan a five-year investment abroad. You need foreign currency, so you exchange domestic currency at the current spot rate. At the same time you want certainty that you can convert back at the end, so you agree a forward rate for that future exchange. Two transactions, at different times, in opposite directions — that is an FX swap. Locking the forward rate in advance removes the uncertainty entirely.

Which leaves one question: what is a fair forward rate? He answers it backwards, by showing what an unfair one would allow.

The two legs of an FX swap — a spot exchange now and a forward exchange back — and the rate that makes the pair fair
Two exchanges in opposite directions, both agreed today. That is the whole instrument. Click to enlarge

The arbitrage an unfair forward would allow

Assume the domestic interest rate is 0 per cent and the foreign rate is 10 per cent. Then:

  • Borrow 1 million units of the domestic currency at 0 per cent.
  • Convert it to 1 million units of the foreign currency through an FX swap.
  • Lend the foreign currency at 10 per cent.
  • At the end of the period the deposit returns 1.1 million units including interest.
  • Convert the 1.1 million back at the agreed forward rate of 1 for 1, repay the 1 million loan, and pocket 0.1 million as risk-free profit.
His worked example of a risk-free profit when the forward rate does not price the interest rate difference
Five steps to a risk-free hundred thousand — which is precisely why no forward rate is ever left at that level. Click to enlarge

What removes it, and the rate that results

Market participants rush at a profit like that: buying the foreign currency at spot, lending it, selling it back at the forward. The spot market is liquid enough to be relatively unaffected by the demand. The forward rate is not — it moves until the opportunity disappears. In his example the adjustment takes the forward to 1 divided by 1.1, and at that rate converting 1.1 million back yields exactly 1 million: no profit, no loss.

Then the real example, and every number in it is his. One year. A spot rate of S = 1.11165. One million dollars at 5 per cent becomes 1,050,000. The same million converted at spot is 899,564 euros, and at 3 per cent that becomes 926,551. Divide the two totals and you have the forward: F = 1.13324.

Read it that way and the rule underneath is visible without any algebra. The side earning the higher rate grows faster over the same year, so the forward has to sit above the spot to leave both paths equal. Whenever the market drifts from that, someone takes the difference and the drift closes.

A note on the slide itself: the symbolic form printed beside these numbers reads the ratio the other way round, which with the same two rates would put the forward below the spot. The arithmetic above is his and it is self-consistent, so that is what this page follows.

One million dollars at five per cent against its euro equivalent at three per cent over a year, giving the forward rate
Every number here is his, and they check out end to end — which is what makes this the reliable half of the slide. Click to enlarge
A one year swap drawn with a million dollars at five per cent above its euro equivalent at three per cent, the two totals dividing to give the forward rate
His arithmetic in full: 1,050,000 dollars against 926,551 euros, and the forward of 1.13324 that falls out of dividing them.

When parity holds, and when it does not

The reading is binary and he states it that way. CIP = 0 means interest parity holds and the market is in equilibrium. CIP ≠ 0 means a deviation, which indicates either an arbitrage opportunity or a market imbalance such as a supply and demand discrepancy.

Forecasting with it means combining historical data, interest rates and current conditions — and where direct access to spot prices is limited, the theoretical formula can be applied instead.

But he is explicit about why a futures price leaves parity, and the three reasons matter more than the model does:

  • Short contract duration. Interest rate differences between the US and Europe have limited impact over short timeframes.
  • CIP only accounts for interest rates. Spot market demand, the cross-currency basis and liquidity conditions can all cause deviations, and none of them is in the model.
  • Support and resistance levels. Key price levels on the chart may limit the movement, and CIP models do not incorporate them at all.
The three reasons he gives for a contract trading away from the rate covered interest parity would predict
Three reasons the model misses, and the third one is the whole of the earlier lessons in this course. Click to enlarge

Putting parity on the chart

Here is where it becomes usable. He offers a simplified formula for daily and swing trading, and prefaces it with his own caveat: this approach is not 100 per cent precise or definitive, but it provides valuable insight into the chart. What it is genuinely good for is explaining a situation where the rates of two currencies differ and price moves against your expectation — it makes a seemingly illogical movement comprehensible.

Three substitutions turn the theory into a level you can draw:

  • Divide the interest rate by 4, because a futures contract is typically three months.
  • Use bond yields instead of the actual policy interest rate, as a proxy.
  • Use the opening price of the futures contract instead of the spot price.
  • What comes out is an approximation that identifies the market's balance range — an equilibrium area, not a target.
The three substitutions that turn the parity relationship into something usable on a daily chart: a quarter of the rate, bond yields, and the opening price
Three substitutions and it becomes a level. His simplified run gives 1.11716 against a spot of 1.11165. Click to enlarge
The simplified parity calculation applied to a euro futures contract, with the spot and the resulting balance price marked
The simplified version, on a contract. A quarter of the rate, the opening price instead of the spot, and 1.11716 as the balance.

When the differential widens and price goes the other way

This is the payoff, and it is the part worth remembering.

When the interest rate differential between two currencies increases, the market can move in the opposite direction to the one everybody expects. Fundamentally you would expect the currency offering the higher rate to strengthen. What happens instead is that a great many participants sell the lower-rate currency and buy the higher-rate one to replicate the arbitrage — and the mechanisms that counteract that process can weaken the higher-rate currency instead.

That is the trap from earlier in the page, seen from the other end. And it is why the balance price is worth drawing: it does not predict the direction, but it tells you where the equilibrium sits while the crowd is leaning on one side of it.

A widening interest rate differential alongside a currency that weakens instead of strengthening, and the crowd that causes it
The move that looks wrong and is not. The differential widened; the price went the other way. Click to enlarge
A euro futures chart with the interest rate differential marked at each contract opening, moving between 0.25 and 1.25
Each contract opening labelled with the differential that applied to it, from 0.25 up to 1.25.
The same chart extended, with the differential rising through 1.35, 1.50 and 2.00 across successive contract openings
The same instrument as the differential widens — 1.00, 1.25, 1.35, 1.50, then 2.00 — with each contract opening marked.

What to take from this one

Three things, in the order they matter:

  • The symbol is a set of facts, not a name. 6EZ4 is the euro, December, 2024 — 91 days running to the third Friday of the expiry month, with the next contract starting as this one ends. Knowing which contract you are looking at comes before anything you do with it.
  • The interest rate differential is in the price before you arrive. It is what separates the contract from the spot rate, it is set by benchmarks that have themselves changed — LIBOR out, SOFR and ESTR in — and the yield curve is where you look for what it will do next.
  • Parity gives a balance level, not a forecast. He supplies the simplified version specifically so you can draw it, and in the same breath tells you it is not definitive, that it stopped holding universally after 2008, and that levels on the chart will override it. Use it to understand a move that looks illogical, not to predict one.
Three panels: the symbol is a set of facts, the differential prices the contract, and parity gives a level rather than a forecast
Where the lesson ends up — and the balance level drawn against the real contract, openings and all. Click to enlarge
A euro futures chart with the parity balance drawn against each contract opening and the differential labelled on each
The balance level against price, contract by contract. This is the picture the whole lesson builds towards.
The same chart with the closing point and the weighted average marked, the settlement sitting above the parity balance
His own note on it: watch the difference between the close and the weighted average, which settled above the parity balance.

Next: the pairs, one at a time

This lesson treated "a currency pair" as one thing. Lesson ten takes them apart — each symbol with its own average daily range, what a pip is worth in it, and the economy sitting underneath.

Back to the twelve lessons