Understanding the Short Rate
1. Understanding the Short Rate
When we think about interest rates, we often refer to the 1-year, 5-year, or even 30-year yields. But if we zoom in to the very beginning of the term structure — to an infinitesimally small point in time — we encounter the short rate, denoted mathematically as $r(t)$.
In this video, we explore the concept of the short rate. It’s not a rate you can observe directly in the market, yet it’s the foundation upon which many financial models — especially in quantitative finance and FRM studies — are built.
Think of the short rate as a speedometer for interest rates. It tells you the rate of return for lending money over an infinitesimal period. This value evolves over time, driven by both a trend (drift) and randomness (volatility), which is precisely what interest rate models aim to capture.
Watch the video below to get an intuitive grasp of this critical concept:
Whether you’re just starting out or deep into your FRM preparation, understanding the short rate will unlock your ability to model bond prices, forward rates, and yield curves with confidence.
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