---
title: Duration
description: Duration explained: how bond price sensitivity to yields works, desk rules of thumb by tenor, and a worked P&L example on a 6bp move.
source: Helious
canonical: https://helious.io/learn/duration
---

# Duration

**Duration** measures a bond’s price sensitivity to interest rates: a duration of 8 means the price moves roughly 8% for every 100 basis point change in yield (in the opposite direction). Technically it is the weighted average time to receive a bond’s cash flows, but on a desk it is used almost exclusively as a risk multiplier.

Traders live in duration terms because yield moves alone say nothing about P&L. A 10bp move is trivial in a 3-month bill and painful in a 30-year bond, purely because of duration. Portfolio managers express macro views by going “long duration” (betting yields fall) or “short duration” (betting they rise), and hedge auction supply by selling matching duration ahead of the sale.

- Rules of thumb: 2-year note ≈ 1.9, 10-year note ≈ 8, 30-year bond ≈ 16–17.
- Lower coupons and longer maturities both raise duration; convexity makes the true relationship slightly curved for big moves.

**Worked example:** You hold $50 million of 10-year notes with duration 8.1. A weak auction tails 3bp and 10-year yields rise 6bp on the day. Estimated P&L: −6bp × 8.1 × $50m = −$243,000. The identical 6bp move on $50 million of 2-year notes (duration 1.9) would cost only about $57,000.

## Questions

### What is duration in bonds?

The sensitivity of a bond's price to a change in yield, expressed in years. A bond with a duration of 8 loses roughly 8% of its price if yields rise one percentage point. It is the number that converts a yield move into money.

### Why does duration matter for the long end?

Because it compounds: a 30-year bond has far more duration than a 2-year note, so the same yield move costs far more at the long end. That is why a bear steepener hurts and why a weak 30-year auction moves markets more than a weak 2-year one. Helious publishes the per-tenor moves in basis points on [the rates board](https://helious.io/rates).

## Live data

Helious measures this and publishes the current figures at [https://helious.io/learn/duration](https://helious.io/learn/duration), and through the get_auctions and get_rates_and_curve tools on its MCP server at https://helious.io/mcp.