A
AcadiFi
SF
sf_fintech2026-05-21
cfaLevel IFixed IncomeModified Duration

How do I use modified duration to estimate a bond price change?

I know duration and price move opposite to yield, but I keep mixing up whether to use 25, 0.25, or 0.0025 for a 25 basis point yield move.

44 upvotes
Verified ExpertVerified Expert
AcadiFi Certified Professional

Use the decimal yield change. The first-order estimate is:

percentage price change approximately equals -modified duration x change in yield

If modified duration is 6.4 and yield rises by 25 basis points, the decimal yield change is 0.0025. The estimated price change is -6.4 x 0.0025 = -0.016, or -1.60 percent.

The negative sign captures the inverse relationship between price and yield. If yield falls by 25 basis points, the estimate becomes positive.

📊

Master Level I with our CFA Course

107 lessons · 200+ hours· Expert instruction

#modified-duration#basis-points#price-sensitivity