Don't trust us — run the numbers yourself

This page lays the whole NCSX-IS computation bare: it just fetched the constituent data and the official published value live, and is now executing the formula bond by bond in your browser, then the face-value weighting. If our number were wrong, it would fall apart right here. Formula: spread_i = (coupon_i − UST_i) × 100, face-value-weighted sum.

Fetch (live, just now)

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Recompute each bond's at-issuance spread

Each row's UST is the Treasury-curve interpolation at that bond's pricing date (data and interpolation method are public on the methodology and data pages). "Recomputed" is calculated by your browser on the spot; "Published" comes from the official JSON.

Bond	Coupon	Pricing	UST	Recomputed	Published	Face value	Weight	SEC filing
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Face-value weighting

Weight = bond face value ÷ total face value; index = Σ weight × recomputed spread.

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Check against the official published value

Scope and red line: this page verifies the arithmetic consistency of the at-issuance spread layer — bond terms come from SEC filings (every row links back to the source), UST from the official Treasury curve. It is not a valuation, not a rating, and not investment advice; secondary-market traded spreads are outside this layer (they require licensed TRACE data, and we do not fill demo numbers). If any row fails to reconcile, tell us via the contact page — corrections re-version the dataset and get a new DOI.