Intra-Curve and Inter-Curve Swap Spreads (CFA Level 1): Defining Intra-Curve Swap Spreads, Typical Intra-Curve Spread Formula, and Defining Inter-Curve Swap Spreads. Key definitions, formulas, and exam tips.
It’s very common to hear traders discuss “the 2s10s spread” or “the USD–EUR spread” as if they’re describing daily weather forecasts in the financial markets. At first, I found the jargon a bit overwhelming: Are we talking about the same yield curve, or are we crossing from one currency to another? The world of swaps involves both intra-curve spreads (differences within one yield curve) and inter-curve spreads (differences between two or more yield curves denominated in different currencies). If you’re feeling a little unsure, don’t worry—by the end of this discussion, you’ll see how these spreads work, how they’re traded, and why they’re so crucial to interest rate and macro strategies.
Intra-curve swap spreads compare swap rates of different maturities along the same yield curve. Perhaps the most popular reference is the difference between the 2-year swap rate and the 10-year swap rate on the same currency’s yield curve (like the USD LIBOR swap curve, or nowadays more commonly a SOFR-based swap curve). This spread is often used as a stand-in for the slope or shape of that segment of the yield curve.
Why do we care about differences between, say, 2-year and 10-year rates? The shape of the yield curve can tell us a lot about market expectations for economic growth, central bank policy, and inflation. For instance:
Firms and traders who enter “flattener” or “steepener” trades in swaps do so by receiving (or paying) fixed in one maturity and paying (or receiving) fixed in another. Essentially, they position themselves to profit from changes in the slope of the curve. If they expect the curve to steepen, they might receive fixed at the short maturity and pay fixed at the longer maturity, hoping the difference widens.
A common way to represent an intra-curve spread is:
$$ \text{Intra-Curve Spread}_{(T_1, T_2)} = \text{SwapRate}(T_2) - \text{SwapRate}(T_1) $$
where \( T_1 \) and \( T_2 \) are two distinct maturities. For example, a “2s10s” spread might be:
$$ \text{2s10s Spread} = S_{10} - S_{2} $$
If this difference is historically low, some market participants might anticipate a return to normal levels—say, if typically the difference is 1.50% but it’s currently only 0.75%. They’ll consider trades that benefit if the curve steepens back to more “average” conditions.
Below is a quick Python snippet that calculates a sample 2s10s intra-curve spread:
1import math
2
3S2 = 0.025 # 2-year swap rate (2.5%)
4S10 = 0.040 # 10-year swap rate (4.0%)
5
6intra_curve_spread = S10 - S2
7print(f"Intra-curve spread (10y-2y) = {intra_curve_spread*100:.2f} bps")
This simple script just prints out a 1.50% (150 bp) spread. In real life, you’d have to incorporate discount factors, day-count conventions, and the specific currency’s standard quoting methods, but the idea remains the same.
While intra-curve spreads stay within one currency, sometimes the opportunity lies in comparing two entirely different yield curves, such as the USD swap curve versus the EUR swap curve. This is known as an inter-curve swap spread. So if a trader believes the Federal Reserve will keep rates on hold while the European Central Bank (ECB) might hike aggressively, you might see a difference in the relative shape of these curves.
Inter-curve spreads help clients and traders:
A typical scenario is cross-currency basis swaps, where you exchange principal and interest flows in one currency for principal and interest flows in another. Your net exposure depends on the difference in swap rates and the basis, which can fluctuate due to capital flows, liquidity conditions, and global macro events.
Here’s an overview in a quick diagram that shows how we can think about intra-curve and inter-curve spreads:
graph LR
A["USD Swap Curve"] --> B["Intra-Curve Spread <br/> (2Y vs 10Y)"]
A --> C["Inter-Curve Spread <br/> (USD vs EUR)"]
B --> D["Potential Gains from <br/> Flattening/Steepening"]
C --> E["Cross-Currency Basis <br/> (USD/EUR)"]
Many types of market participants get involved in swap spreads:
In short, if there’s an opportunity for profit, traders will look at yield curve spreads—both within a curve and across multiple curves—to see if they can find an anomaly or position themselves ahead of expected macro events.
When placing an intra-curve trade, let’s say you foresee that the yield curve will flatten (i.e., the spread between the 2-year and 10-year points will narrow). One strategy is:
If the 2-year rate rises relative to the 10-year (which means the spread tightens), you’ll earn a profit on that relative move. Conversely, if you think it will steepen, you flip it around:
For an inter-curve swap spread trade, imagine you think the U.S. economy is slowing, so the Federal Reserve might cut rates, but the European economy is heating up, prompting the ECB to raise rates. You might:
You’re effectively long the USD swap curve and short the EUR swap curve. Your net payoff depends on how each curve moves. Of course, this is simplified: in real trades, you’ll incorporate cross-currency basis swaps, notional amounts would be matched or partially matched, and you’ll watch the offsetting currency exposures carefully.
Picture the aftermath of a major central bank announcement. Back in my earlier days, I remember the Fed unexpectedly signaling a more dovish stance. The U.S. 2-year rate quickly fell 20 basis points, while the 10-year rate fell only 10 basis points. Traders who had anticipated a flattening by paying short-term rates and receiving longer-term rates saw that 2s10s spread compress. Their positions generated tidy gains.
Alternatively, in a cross-currency scenario, if the ECB was aggressively hiking while the Fed stayed put, the EUR curve might rise faster. A receiving position in USD swaps combined with a paying position in EUR swaps could see nice profits as the gap between USD and EUR swap rates widened.
A wide range of macroeconomic conditions can push these spreads:
Moreover, short-end rates are often more sensitive to central bank policy, while longer-end rates sometimes reflect inflation expectations or broader growth views. That’s why the shape between short and long maturities can shift quickly after new information hits the market.
Let’s not forget that swap spread trades—whether within a curve or across curves—come with risks:
A robust risk management framework typically involves setting risk limits for each part of the curve or each currency segment, stress-testing scenarios (e.g., a flattening vs. steepening shock, or a sudden cross-currency spread blowout), and ensuring the net exposure remains in line with the firm’s or portfolio’s overall risk tolerance.
Sometimes you’ll hear about “butterfly” trades, which involve taking positions at three different maturities—a short-dated, a medium-dated, and a long-dated point—aiming to profit from changes not just in slope but in the curve’s curvature. If the middle maturity is mispriced relative to the other two, a butterfly position could realize gains.
Similarly, advanced inter-curve strategies might target a “roll-down” effect—where if you receive on a steeper part of the curve, you benefit as your position “rolls down” into lower-yield territory over time. Of course, the complexity—and the risk—ramps up when you add more legs and multiple currencies.
I recall a day when a bank’s prop desk had a big bet on the 5s30s slope (another typical spread for measuring curve shape). The rationale was that the Federal Reserve would keep short-end rates stable, but inflation fears would pop, pushing the 30-year rate higher. They took a steepener position. Sadly (for them), a negative economic data surprise pushed all rates lower, but the 30-year dropped more than the 5-year. Boom—flattening instead of steepening. They closed out with a loss. Moral of the story? Even well-researched curve trades can turn quickly if the market narrative changes.
Large-scale events—like the Great Financial Crisis or the COVID-19 pandemic—complicate yield curve analysis. At times, central banks intervene heavily, purchasing long-dated securities (QE) or introducing special lending facilities. Such interventions can create artificially tight or wide spreads. Meanwhile, cross-currency markets may lock up, leading to big swings in cross-currency bases. Being mindful of these extraordinary factors is essential for successful (and safe) swap spread trading.
You’ll see that understanding intra-curve and inter-curve swap spreads is crucial to navigating the interest rate landscape. They’re powerful tools for expressing a macro view, hedging interest rate risk, or extracting relative value opportunities. Here are a few key exam tips:
These points often show up in exam questions involving scenario-based yield changes or multi-part item sets that ask you to calculate the net payoff of a combined swap position. Knowing how to break down the legs of the trade and identify the final exposures is your ticket to top marks.
Remember, analyzing the shape of yield curves—and the differences across currency curves—can become second nature once you practice enough. Keep at it, reflect on real market events, and you’ll develop an intuition for how these spreads behave.
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