# Slope Naming Convention Source: https://www.yieldcurve.pro/learn/slope-naming-convention Traders and analysts use a compact shorthand to name yield curve spreads. The convention encodes both tenors into a single label. **Year tenors** use the number followed by **s** (for "years"): 2s = 2-Year, 5s = 5-Year, 10s = 10-Year, 30s = 30-Year. **Month tenors** use the number followed by **m** (for "months"): 3m = 3-Month, 6m = 6-Month. The **short tenor** comes first, the **long tenor** second. The spread itself is always long minus short. Common examples: - **2s10s** = 10-Year minus 2-Year (the most widely tracked slope) - **3m10y** = 10-Year minus 3-Month (the Fed's preferred recession indicator. The "y" suffix avoids ambiguity with "3s" meaning 3-Year) - **2s30s** = 30-Year minus 2-Year - **5s30s** = 30-Year minus 5-Year The **y** suffix (as in 3m10**y** or 1**y**2y) appears when clarity requires distinguishing years from other units. In practice, context resolves most ambiguity, so 2s10s rather than 2y10y is standard. A positive spread means the curve is upward-sloping between those two tenors. A negative spread means it is inverted. The absolute level, direction of change, and speed of change all matter for [regime classification](https://www.yieldcurve.pro/regimes) and trading decisions. ## Why the Shorthand Exists The convention comes from the trading floor, where a spread has to be named out loud, fast, without ambiguity. Saying "the ten year minus two year spread" takes seven words. Saying "twos tens" takes two, and it carries the same information. The compression matters when a trader is quoting several spreads in a row. The plural form is the reason for the s. Traders say "twos" for the 2 Yr and "tens" for the 10 Yr, because the security is one of many bonds at that maturity rather than a single instrument. The written shorthand simply records how the label is spoken. The order is fixed by the same logic. The shorter tenor is named first because it is the reference point. The spread then reads as a movement outward along the curve, which matches how a trader thinks about the position. ## Reading Any Label Three rules decode every label you will meet. 1. **Split the label into two tenors.** Each part is a number plus a unit letter. `2s10s` splits into `2s` and `10s`. `3m10y` splits into `3m` and `10y`. 2. **Read the unit letter.** An `s` or a `y` means years. An `m` means months. So `3m` is 3 Mo and `3s` is 3 Yr, which is exactly the ambiguity the `y` suffix exists to prevent. 3. **Subtract the first from the second.** The spread is always the longer tenor minus the shorter one, so the first tenor named is the one subtracted. Apply the rules to `5s30s`. Split into `5s` and `30s`. Both are years. The spread is the 30 Yr yield minus the 5 Yr yield. A reading of +40 bps means the 30 Yr yields 40 bps more than the 5 Yr. The same rules handle the mixed cases. `1y2y` is the 2 Yr yield minus the 1 Yr yield, with the `y` used on both sides for symmetry. `3m2y` is the 2 Yr yield minus the 3 Mo yield. ## Where the Convention Breaks Down The shorthand is a market habit rather than a standard, so it has soft edges worth knowing about. **The `y` is optional and inconsistent.** `2s10s` and `2y10y` name the same spread. Both appear in research. Neither is wrong, and only `2s10s` is common in US Treasury markets. **Three tenor labels mean a different trade.** A label such as `2s5s10s` names a [butterfly spread](https://www.yieldcurve.pro/learn/butterfly-spread) rather than a slope. It has three legs, and the middle tenor is the belly. The arithmetic is not a simple subtraction, and the sign convention varies by desk. **Other markets use their own units.** Non-US curves and swap markets often quote in years with a `y` throughout, and money market curves may name instruments rather than tenors. The Treasury convention on this page does not transfer automatically. **A label does not fix the data source.** `2s10s` computed from constant maturity par yields and `2s10s` computed from on-the-run securities are close but not identical. On this site every spread is built from the published par curve, which keeps the series consistent over time. ## FAQ ### Why is it 2s10s and not 10s2s? Because the shorter tenor is named first by convention, and the spread is always calculated as the longer yield minus the shorter one. Naming it the other way round would suggest the opposite subtraction and flip the sign of every quoted value. ### What does the y in 3m10y do? It removes an ambiguity. Written as `3m10s`, the second tenor could be misread, and written as `3s10s` the first tenor would mean 3 Yr rather than 3 Mo. Using `y` for the year leg makes the mixed unit case unmistakable. The suffix is only needed where confusion is possible, which is why the pure year spreads keep the simpler `s` form. ### Does a negative spread always mean recession is coming? No. A negative spread means the curve is inverted between those two tenors, which historically has often preceded a recession but is not a mechanism that causes one. Different pairs also invert at different times and by different amounts, so the choice of spread changes the signal. The [3m10y spread](https://www.yieldcurve.pro/learn/3m10y-spread) and the [2s10s spread](https://www.yieldcurve.pro/learn/2s10s-spread) have disagreed for months at a time.