Fixed Income Fund Ownership Tracker — SEC N-PORT

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Who holds this bond? Reverse-lookup any CUSIP or ISIN across 12,000+ registered mutual funds and ETFs using SEC Form N-PORT — the same quarterly holding disclosure that institutional desks pay Bloomberg PORT and BlackRock Aladdin tens of thousands per year to aggregate.

The Problem

Fixed income markets manage over $50 trillion in U.S. outstanding debt, yet buy-side positioning data remains one of the most opaque corners of capital markets. Unlike equities — where 13F filings are commoditized — bond holder intelligence is locked behind enterprise terminals or scattered across thousands of unstructured EDGAR filings.

Form N-PORT changed this in 2019. Every registered U.S. fund must now disclose its complete portfolio monthly, including CUSIP-level detail on coupon, maturity, par value, fair value, issuer category, and asset classification. This actor turns that raw regulatory data into structured, queryable ownership intelligence — in under 2 minutes.

Five Query Modes

1. CUSIP Lookup — "Who holds this bond?"

Enter any 9-character CUSIP. Get every fund holding that security, sorted by position size, with fair value, % of NAV, and filing-date detail.

{
"mode":"cusip_lookup",
"cusip":"037833BS8",
"max_results":500
}

Example result: Apple Inc 3.2% bond held by 2,494 funds totaling $7.64B in disclosed fair value.

2. ISIN Lookup

Same as CUSIP lookup but using a 12-character ISIN — useful for cross-referencing Euroclear/Clearstream identifiers or for securities where the ISIN is easier to source than the CUSIP.

{
"mode":"isin_lookup",
"isin":"US037833BS80"
}

3. Issuer Search — Full Exposure Mapping

Surface every holding from a given issuer across the full N-PORT universe. Partial matching supported — "JPMORGAN" captures all JPM-issued debt regardless of subsidiary or entity.

{
"mode":"issuer_search",
"issuer_name":"FORD MOTOR"
}

Use case: Pre-trade intelligence for a new issue. Which accounts already hold existing paper from this issuer?

4. Concentration Analysis — Crowded Trade Detection

Quantifies how concentrated ownership is for any CUSIP using the Herfindahl-Hirschman Index (HHI). Returns top-10 holders ranked by fair value, aggregate holder count, and distribution statistics.

{
"mode":"concentration_analysis",
"cusip":"037833BS8"
}

HHI > 2,500 = highly concentrated register. Monitor for forced-selling risk in stressed credits.

5. Category Filter — Sector-Level Screening

Screen the entire N-PORT universe by issuer type or asset class. Particularly valuable for agency, muni, and structured credit markets where holder data is otherwise nearly impossible to source.

By issuer category:

By asset category:

{
"mode":"filter_by_category",
"filter_type":"issuer_category",
"filter_value":"MUN",
"max_results":1000
}

Output Structure

Each run returns a single JSON result with:

{
"query":{"type":"cusip_lookup","cusip":"037833BS8"},
"security_info":{
"cusip":"037833BS8",
"issuer":"APPLE INC",
"title":"APPLE INC 3.2% 2025",
"coupon_rate":3.2,
"maturity_date":"2025-05-11",
"issuer_category":"Corporate",
"asset_category":"Debt Security"
},
"summary":{
"total_fund_holders":2494,
"total_fair_value_across_funds":7640000000.00,
"avg_fair_value_per_fund":3063738.00
},
"holdings":[
{
"registrant":"VANGUARD FIXED INCOME SECURITIES FUNDS",
"fund_name":"Vanguard Total Bond Market Index Fund",
"cusip":"037833BS8",
"isin":"US037833BS80",
"issuer_name":"APPLE INC",
"security_title":"APPLE INC 3.2% 2025",
"issuer_category":"Corporate",
"asset_category":"Debt Security",
"coupon_rate":3.2,
"maturity_date":"2025-05-11",
"coupon_type":"Fixed",
"fair_value_usd":485000000.00,
"par_value":480000000.00,
"pct_of_fund_nav":0.18,
"fund_total_assets":320000000000.00,
"fund_net_assets":318000000000.00,
"is_in_default":"N",
"interest_in_arrears":"N",
"is_pik":"N",
"filing_date":"2024-09-30",
"accession_number":"0000932471-24-021583"
}
]
}

Who Uses This

Data Source & Coverage

• Source: SEC EDGAR Form N-PORT Quarterly Bulk Data (DERA public dataset)
• Universe: ~12,000+ registered open-end funds, ETFs, and variable annuity portfolios
• Coverage: All SEC-registered fund AUM — approximately $30 trillion in disclosed assets
• Lag: ~60 days from fiscal quarter-end to public availability
• Asset classes: IG/HY corporate bonds, U.S. Treasuries, agency MBS, municipal bonds, CLOs, ABS, convertibles, sovereign debt, TIPS
• Not included: Hedge funds, private funds, separately managed accounts, insurance general accounts, and foreign entities not registered with the SEC

Pricing

Pay-per-event — pay only for what you run.

Example costs:

• CUSIP lookup returning 100 holders: $1.60 (start + 100 items)
• CUSIP lookup returning 500 holders: $5.60 (start + 500 items)
• Issuer search returning 1,000 holdings: $10.60

For comparison: Bloomberg PORT charges approximately $2,000/month for similar institutional ownership analytics. This actor delivers the same underlying EDGAR data with no subscription required.

Technical Specifications

Limitations

• Holdings data is quarterly point-in-time, not real-time intraday flow data (see FINRA TRACE for real-time trade reporting)
• ~60-day publication lag from each quarter-end
• Only covers SEC-registered open-end funds and ETFs registered under the Investment Company Act of 1940
• Position fair values reflect fund-reported methodology (mark-to-market, matrix pricing, BVAL) and may differ from mid-market prices

Legal Notice

This actor accesses exclusively public data from SEC EDGAR. All data originates from official mandatory regulatory filings in the public domain (17 C.F.R. § 270.30b1-9). Not affiliated with or endorsed by the U.S. Securities and Exchange Commission. Users are responsible for compliance with applicable regulations governing the use of securities holdings data in their jurisdiction.