Sovereign Yield Curve Construction
The process of deriving a continuous zero-coupon or par yield curve from observed Indian G-Sec market prices, using methodologies such as Nelson-Siegel or cubic spline fitting, with CCIL and NSE publishing reference sovereign yield curves used for valuation and risk management.
India's sovereign yield curve was constructed from traded prices of outstanding dated G-Securities across various maturities in the NDS-OM market. Because the G-Sec market did not have a liquid instrument for every tenor, curve construction required interpolation and smoothing techniques to derive yields at standardised maturities (1-year, 2-year, 5-year, 10-year, 30-year, etc.).
The primary reference curve publisher was CCIL (Clearing Corporation of India Limited), which used traded prices from NDS-OM to construct and disseminate reference sovereign yields daily. CCIL applied a Nelson-Siegel-Svensson model, which parameterised the yield curve using level, slope, and curvature factors to produce smooth curves consistent with observed market prices. The NSE also maintained a government securities yield curve under FBIL (Financial Benchmarks India Private Limited) oversight.
FBIL became the designated administrator for Indian financial benchmarks following RBI's 2018 notification, and the FBIL government securities yield curve (daily zero-coupon curve for maturities from 0.25 to 40 years) became the industry reference for multiple applications: valuation of AFS/HFT portfolios in bank balance sheets under RBI's investment valuation norms, duration and DV01 computation, pricing of derivatives such as interest rate swaps, and benchmarking of G-Sec mutual funds.
The yield curve reflected the term structure of risk-free rates in India — its shape conveyed important information: an upward-sloping curve (normal) implied expected higher future rates or risk premium for duration; an inverted curve (rare in India) signalled rate cut expectations; a humped curve suggested a complex rate outlook.
For mutual fund managers, the sovereign yield curve was the foundational building block for relative-value analysis — assessing whether a particular G-Sec was rich or cheap relative to the curve, which informed portfolio positioning in duration funds, gilt funds, and target maturity funds.