Duration Risk in Debt Funds: What Investors Must Know — SkimNews
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- Debt mutual funds see NAV changes when interest rates move, with longer-duration portfolios experiencing larger swings, according to Sanjiv Bajaj, Joint Chairman & MD of BajajCapital Ltd.
- Modified duration works as a rule of thumb: a fund with modified duration of four years could see roughly a 4% portfolio value change for a 1 percentage-point move in yields, in the opposite direction, assuming other factors hold.
- Yield curve shifts are rarely uniform and convexity also affects outcomes, so the duration rule should be treated as an approximation rather than a precise forecast, Bajaj said.
- Fund categories—liquid, ultra-short, short-duration, medium-duration, dynamic bond and gilt—carry materially different interest-rate exposures because their mandates and portfolios differ.
- Credit quality matters separately from duration: investors should check how much of the portfolio sits in sovereign, highly rated, and lower-rated securities, since interest-rate risk and credit risk must be assessed independently.
- Debt funds are not fixed deposits: their NAV reflects the market value of underlying securities, which moves with interest rates and market conditions, and investors should also weigh expense ratio and exit load alongside duration.
- Horizon alignment is the key takeaway: matching a fund's duration to one's own investment horizon is what determines whether interim NAV swings translate into realized losses or just paper volatility, Bajaj said.
Why it matters: Investors who pick a debt fund by category label alone may misjudge their actual rate exposure—two funds called "short-duration" can sit on very different modified durations, and a horizon-mismatch is what turns a paper NAV dip into a realized loss when an investor exits early.
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