What Is a 13F-HR Filing? Institutional Holdings Explained

Who files 13F-HR?

Section 13(f) of the Securities Exchange Act of 1934 requires every institutional investment manager (IIM) that exercises investment discretion over $100 million or more in Section 13(f) securities to file a quarterly 13F-HR report. The threshold is measured on the last trading day of any month during the calendar year — once crossed, the manager files for the entire remaining calendar year even if assets subsequently drop below $100M.

Section 13(f) securities are primarily exchange-traded equity securities and certain options, warrants, and convertibles. Fixed income, private equity, and unlisted positions are excluded.

The types of institutions that file include:

• Hedge funds — long/short equity funds, quantitative funds, activist funds
• Mutual funds — including index funds, actively managed equity funds
• Pension funds — state pension systems, corporate pension plans
• Registered investment advisors (RIAs) — wealth management firms, family offices above the threshold
• Banks and insurance companies — with investment discretion over equity portfolios

As of 2026, roughly 5,000-6,000 institutional managers file 13F-HR each quarter. The filing universe grows as new managers cross the $100M threshold. High-profile filers include Berkshire Hathaway, Renaissance Technologies, and Bridgewater Associates — though Bridgewater's public 13F represents only the portion of its strategy exposed to long U.S. equity positions.

The 45-day filing delay

The most important constraint on 13F analysis is the 45-day filing lag. Managers must file within 45 calendar days of the quarter end. For the standard calendar-year reporting quarters, this means:

The 45-day window was designed to prevent front-running — giving managers time to exit or adjust positions before the public knows their holdings. For analysts, this means 13F data is inherently backward-looking. By the time you read a 13F, up to 6.5 months may have passed since the oldest position shown was established (a position first reported in a Q1 filing that was held since January 1).

The SEC periodically considers shortening the filing window or requiring more frequent reporting. A 2022 SEC proposal to add a monthly amendment requirement for large positions was withdrawn but may resurface. Until then, the 45-day lag is a structural feature of 13F analysis that every analyst must account for.

What 13F-HR discloses

Each 13F-HR filing contains a tabular list of positions. For every holding, the filing discloses:

• CUSIP — the security identifier. Not the ticker (though Form4API maps CUSIPs to tickers automatically).
• Issuer name and security title — the company name and share class.
• Market value — the position's value at quarter end, in thousands of dollars.
• Shares or principal amount — number of shares held as of quarter end.
• Put/call indicator — whether the entry is a call option, put option, or direct equity holding.
• Investment discretion type — Sole (full discretion), Shared (voting or investment authority shared), or Other.
• Voting authority — how many shares the manager votes solo, shares, or has no authority over.

What 13F does not disclose:

• Short positions (including positions held via swaps or CFDs)
• Cash and fixed income holdings
• Private equity or unlisted positions
• Intra-quarter trading activity (only the end-of-quarter snapshot)
• Cost basis or unrealised gain/loss

The put/call indicator deserves special attention. When a manager holds long-dated put options, that appears in the 13F as a "put" entry. This is sometimes mistakenly read as a long equity position. A large put position in the 13F can indicate hedging or a net-short thesis via derivatives — the opposite of a bullish signal.

13F-HR vs 13D vs 13G — what's the difference?

The SEC uses different "13" form types for different disclosure obligations under Section 13 of the Exchange Act. These are not the same form:

• 13F-HR — the quarterly portfolio disclosure for any manager with $100M+ in qualifying assets. Filed by thousands of institutions. Reports long positions only. No ownership threshold — you can report a 0.1% position. Low-urgency quarterly reporting.
• Schedule 13D — the "beneficial ownership report" required when any person or group acquires more than 5% of a publicly traded class of equity with intent to influence or change control of the company. Filed within 10 days of crossing 5%. Amendments required within 2 business days of any material change. The "activist" disclosure — filing a 13D signals potential shareholder activism, board campaigns, or M&A.
• Schedule 13G — the "passive ownership report" — same 5% ownership threshold as 13D but for holders who are passive investors without intent to influence the company. Index funds, ETF sponsors, and institutional passive holders typically file 13G. Less urgency: initial filing within 45 days of year end (or 10 days after crossing 5% for non-qualified filers). Much less signal-bearing than 13D.

For insider-trading analysis, 13F complements Form 4 at the institutional level: Form 4 tells you what company insiders are doing; 13F tells you what large institutional holders are doing. Schedule 13D is perhaps the highest-signal of the three — a new activist 13D filing is often a precursor to corporate events that move stock prices significantly.

Cross-referencing 13F with Form 4

One of the most powerful analytical approaches in public SEC data is combining 13F institutional holdings with Form 4 insider transactions for the same equity. The two data sources are complementary:

Confluence signal: insider buying + institutional accumulation

When company insiders are purchasing shares on the open market (Form 4 code P) at the same time that new institutional 13F filings show increasing positions, the combined signal is stronger than either alone. Corporate insiders have access to company-specific information unavailable to institutions; large institutions provide independent valuation support. Both arrows pointing in the same direction represents multi-source conviction.

Divergence signal: insiders selling while institutions accumulate

The inverse is equally interesting: Form 4 shows insider sales (particularly large, open-market sales not attributable to scheduled 10b5-1 plans or tax withholding), while 13F shows new institutional accumulation. This divergence — insiders exiting while institutions buy — is worth investigating. It may indicate that institutions are acting on a thesis the insiders disagree with, or that insiders are selling for personal liquidity reasons unrelated to corporate outlook.

The lag mismatch

There is an important timing asymmetry: Form 4 is filed within 2 business days of the transaction, while 13F may reflect positions from up to 45 days ago. This means that when you observe a new 13F showing institutional accumulation, insiders may have already been buying for weeks before that institutional buildup appeared publicly. Leading with Form 4 data and using 13F as confirmation is generally the more time-sensitive approach. Form4API surfaces both in one API, letting you join them by ticker without managing two separate data pipelines.

How to access 13F-HR data programmatically

There are two main routes to 13F data in code:

1. Direct SEC EDGAR (free, complex)

EDGAR publishes every 13F-HR filing as XML. The primary challenge is the CUSIP-to-ticker mapping — 13F uses CUSIPs, not tickers, and the mapping table must be maintained separately. A second challenge is that 13F XML schemas have changed over the years, requiring version-aware parsing. Expect 400-600 lines of robust parsing, mapping, and normalisation code to build a production-grade 13F pipeline from EDGAR directly.

2. Form4API /v1/holdings (developer-friendly)

Form4API parses 13F-HR filings and exposes holdings as JSON with ticker already resolved and manager metadata joined:

# Get all institutional holders of NVDA as of latest quarter
curl "https://api.form4api.com/v1/holdings?ticker=NVDA&per_page=20" \
  -H "X-Api-Key: $FORM4API_KEY"

# Get all holdings reported by a specific manager (quarter param is the quarter-end date)
curl "https://api.form4api.com/v1/holdings?manager_cik=0001336528&quarter=2026-03-31" \
  -H "X-Api-Key: $FORM4API_KEY"

The response includes: ticker, CUSIP, manager name and CIK, shares held, market value, put/call type, and the reporting quarter. You can cross-reference with /v1/transactions on the same ticker to compare institutional positioning against insider Form 4 activity.

The /v1/holdings endpoint is available on the Business tier. The Free tier covers 15,000 calls per month at no cost for Form 4 transaction data. See /docs for the full API reference.

Common 13F pitfalls

• Treating 13F as real-time data. The 45-day lag means 13F reflects the past, not the present. Positions shown in a Q1 filing could have been fully exited by the time you read it. Never treat 13F as a current snapshot.
• Ignoring the put/call column. A large "put" entry in 13F is not a long position — it is a long put option, which profits when the stock falls. Failing to check the put/call indicator will cause you to misread bearish derivative positions as bullish equity holdings.
• Not resolving CUSIP-to-ticker manually. Raw EDGAR 13F data uses CUSIPs. If you roll your own pipeline and use a stale mapping table, you will misattribute positions to the wrong companies — especially common around corporate actions (mergers, spin-offs, class-share changes).
• Conflating 13F with 13D/13G. These are different forms with different disclosure triggers. Adding 13D activism signals into a 13F holdings dataset will produce analytical noise — treat them as separate data streams.
• Double-counting fund families. A single asset manager (e.g., Vanguard) files multiple separate 13F reports for different registered investment companies (funds). Summing shares across all Vanguard 13F filings will overstate the "total Vanguard position" unless you aggregate at the manager group level.
• Missing mid-quarter changes. A fund that bought 1M shares in January and sold them all in February will show zero in the March 31 quarter-end filing. The position was real but invisible in the 13F data. Intra-quarter activity is only partially visible through Form 4 data for positions held by insiders.

Frequently asked questions