SEC Form 13F filings show what large institutional investment managers hold in their equity portfolios, reported once per quarter. The raw filings are publicly available on EDGAR, but reading them well requires understanding what the data includes, what it excludes, and how to compare holdings across quarters to identify meaningful changes.
This guide covers the practical skills for interpreting institutional holdings data: how to read the fields in a single 13F filing, how to compare filings across quarters to spot new positions, increases, decreases, and exits, and what limitations to keep in mind when drawing conclusions from the data.
For background on who must file, the $100 million threshold, and the regulatory framework, see the companion guide What Is a 13F Filing?.
The Quarterly Snapshot
The most important thing to understand about 13F data is that each filing is a point-in-time photograph, not a continuous feed. The filing reports holdings as of the last calendar day of the quarter — March 31, June 30, September 30, or December 31.
Between that snapshot date and when you see the data, two things have happened:
- The manager had up to 45 days to file. A filing for the quarter ending June 30 might not appear on EDGAR until mid-August.
- The portfolio may have changed. Positions shown on the filing may have been increased, reduced, or eliminated entirely during the gap between the snapshot date and the filing date.
This means every 13F you read describes a portfolio that is at least six weeks old. For hedge funds and other active managers with high portfolio turnover, the current portfolio may bear limited resemblance to what the filing shows. For long-term-oriented managers, the data tends to be more representative of current positioning, though still not guaranteed.
Reading a Single 13F Filing
Each 13F-HR filing contains a cover page and an information table. The information table is where the holdings data lives. Each row represents a single holding, with the following fields.
Issuer Name and Title of Class
The issuer name identifies the company (e.g., "APPLE INC"). The title of class specifies the type of security — "COM" for common stock, "CL A" for Class A shares, "CALL" or "PUT" for options. A single issuer may appear in multiple rows if the manager holds different classes of the same company's securities.
CUSIP
The CUSIP is a nine-character alphanumeric identifier assigned to each security by CUSIP Global Services (operated by the American Bankers Association through S&P Global Market Intelligence). CUSIPs uniquely identify specific securities — the common stock of a company has a different CUSIP from its preferred stock or its convertible bonds. When comparing holdings across filings or across managers, the CUSIP is more reliable than the issuer name, which may vary in formatting between filers.
Share Count
The number of shares held as of the quarter-end date. For equity options, this field reports the number of shares underlying the option contracts rather than the number of contracts. Share count is the most useful field for tracking position changes over time because it is not affected by price movement — unlike market value.
Market Value
The total market value of the position, reported in thousands of dollars. A value of "25,000" in the filing means $25 million, not $25,000. This is a common source of confusion when reading raw 13F filings. The value is calculated as of the last day of the calendar quarter, using closing prices on that date.
Investment Discretion
This field indicates whether the manager has sole investment discretion, shared discretion, or no discretion over the position. Most positions are reported as "SOLE" — the filing manager independently decides whether to buy, hold, or sell. "SHARED" indicates that another entity shares the investment decision. "NONE" is rare and typically appears in complex arrangements where the filer has voting authority but not investment control.
Voting Authority
Three sub-columns show how many shares the manager has sole voting authority over, shared voting authority over, and no voting authority over. These numbers should sum to the total share count for the row. In most cases, the manager has sole voting authority over all shares held, but shared arrangements are common when multiple entities are involved in managing the same assets.
Put/Call Indicator
This field is blank for common stock positions. For options, it indicates whether the holding is a put option or a call option. When this field is populated, the share count reflects the number of shares underlying the option contracts.
Comparing Quarters: Where the Value Is
A single 13F filing tells you what a manager held on one date. The real analytical value comes from comparing filings across quarters to see how positions changed. There are four categories of changes to look for.
New Positions
A holding that appears in the current quarter's filing but was absent from the prior quarter's filing. This means the manager established a new position during the quarter — or, more precisely, that the manager held the position on the last day of the current quarter but did not hold it on the last day of the prior quarter. The manager may have bought and sold the same stock multiple times within the quarter, and only the end-of-quarter snapshot is visible.
Increased Positions
A holding where the share count is higher than in the prior quarter. To illustrate how this comparison works using a historical example: in Berkshire Hathaway's 13F filed for Q4 2018 (the quarter ending December 31, 2018), the filing showed approximately 255 million shares of Apple. The prior quarter's filing had shown approximately 252 million shares. The difference — roughly 3 million additional shares — represented an increased position. This type of comparison is the basic building block of 13F analysis. The example is referenced here to illustrate the mechanics of quarter-over-quarter comparison, not as commentary on any investment decision.
Decreased Positions
A holding where the share count is lower than in the prior quarter. The manager reduced its position during the quarter. As with increases, only the net change between quarter-end snapshots is visible — the manager may have traded the position actively within the quarter.
Exited Positions
A holding that appeared in the prior quarter's filing but is absent from the current quarter. The manager either sold the entire position or reduced it below the reporting threshold. An exit is a complete disappearance from the information table.
A Critical Note on Market Value
When comparing quarters, always compare share counts, not market values. Market value changes reflect two factors simultaneously: changes in the number of shares held and changes in the stock price. A position might show a 20% increase in market value from one quarter to the next while the share count remained unchanged — the entire change was driven by price appreciation. Conversely, a manager might have added shares while the market value declined because the stock price fell. Share count is the clean measure of what the manager actually did.
Limitations to Keep in Mind
13F data is useful precisely because it is standardised, mandatory, and public. But it has structural limitations that affect how the data should be interpreted.
Long-Only Visibility
13F reports only long positions. Short positions, whether outright short sales or short exposure through derivatives, are not reported. A fund that is long $200 million and short $150 million in the same sector will appear on its 13F as having $200 million in long positions with no indication of the offsetting short book. For managers that use long-short strategies — which includes most hedge funds — the 13F presents an incomplete picture of overall positioning and risk exposure.
The 45-Day Delay
As noted above, the filing window of up to 45 days after quarter-end means the data is inherently stale. Many managers file close to the deadline. By the time a filing becomes available on EDGAR, the holdings it reports may no longer reflect the manager's current portfolio.
No Cost Basis
The filing shows market value as of quarter-end but not what the manager paid for the shares. There is no way to determine from a 13F whether a position is profitable or unprofitable, or when the shares were acquired. A position first appearing on a 13F may have been purchased on the first day of the quarter or the last.
Confidential Treatment Requests
Managers may request confidential treatment for specific holdings under Section 13(f). If the SEC grants the request, those positions are omitted from the publicly filed 13F. They are disclosed later — sometimes one or two quarters after the original filing period — in a delayed amendment. Managers typically request confidential treatment when actively building or unwinding a large position and wish to avoid revealing their activity to the market while it is still underway.
Aggregation Across Strategies
Large institutional managers often file a single 13F that aggregates holdings across multiple funds, strategies, or sub-accounts. The filing shows the total position but does not break it down by individual fund or strategy. Two different funds managed by the same adviser — one increasing a position while the other reduces it — would appear as a single net number. The filing represents the manager's aggregate view, not necessarily a single fund's positioning.
Index Fund Considerations
The largest 13F filers by total holdings are index fund managers — Vanguard, BlackRock (through iShares), and State Street (through SPDR). These firms hold nearly every stock in their benchmark indices. Changes in their positions often reflect fund flows (investors adding money to or redeeming from index funds) rather than active investment decisions. An increase in Vanguard's holdings of a particular stock may simply mean that more money flowed into Vanguard's S&P 500 index fund during the quarter, not that an analyst at Vanguard made a deliberate decision to buy more of that stock.
When examining institutional holdings data, it is worth distinguishing between changes driven by index fund mechanics and changes driven by active management decisions. Academic research has studied this distinction extensively — Cremers and Petajisto (2009) introduced the concept of "Active Share" to measure how much a portfolio deviates from its benchmark, which provides a framework for understanding which institutional changes reflect deliberate positioning.
How Akivus Uses This Data
Akivus processes 13F filings through the Thesma API platform, which extracts and structures the holdings data from each filing, performs quarter-over-quarter comparisons, and identifies new positions, increases, decreases, and exits across the institutional holder universe. This processed data surfaces across Akivus products to provide context on institutional ownership alongside other SEC filing types.
Akivus Reports include an institutional holdings section for each company in the Russell 3000, showing which 13F filers hold positions and how those positions changed quarter over quarter. This institutional ownership data is presented alongside Form 4 insider transaction data, providing two complementary lenses on a company's ownership structure: what corporate insiders are doing with their personal holdings and what large institutional managers hold in their portfolios. Akivus Briefs — free company summary pages — surface recent institutional ownership data as part of a broader company snapshot. In each case, the data is presented factually, describing what the filings contain and how positions have changed. For details on the methodology behind how Akivus structures and contextualises filing data, see the Akivus methodology page.