The yield curve is one of the most important tools in all of finance. It shows the relationship between interest rates (yields) and the time to maturity for debt of the same credit quality — typically government bonds, since they are considered the closest to risk-free. In the UK, the gilt yield curve shows the yields on UK government bonds at maturities from 1 month to 50 years.
What the shape tells you
*Normal (upward-sloping)*: Longer-term rates are higher than short-term rates. Investors demand more compensation for tying up money for longer, reflecting both higher uncertainty over long periods and the expectation of higher future short-term rates. This is the 'normal' shape for a healthy growing economy.
*Inverted (downward-sloping)*: Short-term rates are higher than long-term rates. This typically signals that markets expect interest rates to fall, often because a recession is anticipated. An inverted yield curve has historically been one of the most reliable predictors of recession — the US Treasury curve inverted before every US recession since the 1970s.
*Flat*: Short and long-term rates are similar — often a transitional state between normal and inverted. Signals uncertainty about the economic outlook.
*Humped*: Rates rise and then fall, reflecting specific supply/demand dynamics at particular maturities.
Yield curve movements
The curve does not just shift up and down uniformly. Traders decompose movements into:
*Parallel shift*: All maturities move by the same amount. A 50bp parallel shift up means every point on the curve rises 50bps. DV01 measures the impact of a 1bp parallel shift.
*Steepening/flattening*: The spread between long-term and short-term rates changes. A 'bear steepener' means long rates rise more than short rates (curve gets steeper while rates rise overall). A 'bull flattener' means short rates fall more than long rates.
*Twist*: Different points on the curve move in different directions — 2-year rates rise, 10-year rates flat, 30-year rates fall. Creates complex risk that requires separate hedges for each tenor bucket.
Why the yield curve affects the economy
Banks borrow at short-term rates (from depositors and the wholesale money market) and lend at long-term rates (mortgages, corporate loans). A steep yield curve gives banks a wide net interest margin — a healthy spread between their cost of funds and their lending rate — encouraging active lending and supporting economic growth.
An inverted yield curve compresses this margin. Banks earn less from maturity transformation, discouraging lending and potentially contributing to economic slowdown. This is the mechanism by which tight monetary policy (high short-term rates) eventually slows inflation.
The yield curve for the rates desk
For the Rates desk, the yield curve is the primary tool for pricing all interest rate products. Interest rate swaps are priced from the OIS curve. Government bond prices are directly observable on the curve. Swaption volatility surfaces are calibrated to liquid tenor points on the curve. Every rates position can be expressed in terms of its sensitivity to different parts of the yield curve — and hedged accordingly.