Whale Analyzer
Start with the question Form 13F can answer
Form 13F is a quarterly holdings disclosure filed with the U.S. Securities and Exchange Commission by institutional investment managers that meet the rule's conditions. It can help answer which Section 13(f) securities a manager reported at a quarter end and how reported share counts changed between snapshots. It does not, by itself, reveal the manager's complete assets under management, current holdings, trade dates, execution prices, cost basis, short positions, or investment thesis. The SEC describes the reported fields, including issuer, security class, share amount, and quarter-end fair value, in its [1] Form 13F FAQ.
💡 Use precise research language
- Say “reported holdings as of quarter end,” not “current holdings.”
- Say “reported shares increased or decreased,” unless separate evidence establishes a trade date or motive.
- Treat 13F as delayed, limited-scope disclosure data rather than a complete trading ledger.
The $100 million test is not total AUM
The filing threshold applies when accounts over which a manager exercises investment discretion hold at least $100 million in Section 13(f) securities on the last trading day of any month in a calendar year. It is not a test of the manager's total AUM. Cash, securities outside the official 13F list, and other assets do not enter the calculation merely because the manager oversees them. The SEC updates the official list quarterly; securities not on that list, such as open-end mutual fund shares, should not be reported. The governing threshold and filing instructions appear in the [2] official Form 13F and instructions.
Separate the reporting period from the filing date
The information table is a calendar-quarter-end snapshot, and the usual filing deadline is within 45 days after quarter end. Forty-five days is the maximum filing window, not a trading date and not a promise that every manager files on one fixed date. The SEC FAQ also explains that a deadline falling on a Saturday, Sunday, or holiday moves to the next business day. Do not hard-code May 15, August 14, November 14, or February 14 as universal annual deadlines. When reading a filing, compare the current date with periodOfReport; a historical, late, or amended filing may be much older than 45 days. Store both periodOfReport and filedAt: the former identifies the holdings snapshot; the latter records when the document became public.
Verify the value unit before doing arithmetic
A critical format change took effect on January 3, 2023. Updated Form 13F filings report dollar values rounded to the nearest dollar; the former convention reported values in thousands of dollars. Under the old convention, a raw value of 150000 generally meant $150 million. Under the new convention, the same raw number means $150,000. Combining those fields without recognizing the filing version can create a 1,000-fold error. The SEC FAQ documents both the effective date and the change in rounding convention. A reproducible data model should retain rawValue, rawUnit, normalizedValueUsd, and the rule used for conversion.
| Check | Former convention | From Jan. 3, 2023 |
|---|---|---|
| Reported unit | Thousands of dollars | Dollars |
| Raw value 150000 | $150,000,000 | $150,000 |
| Audit storage | Raw value plus x1000 flag | Raw value plus USD flag |
Separate trading from price movement
A change in market value is not proof of a purchase or sale. Normalize shares and value first, then calculate an implied quarter-end price for the same security: implied price = reported value in dollars ÷ reported shares. The following is a hypothetical calculation for the same common-stock class with no split, not a historical holding: Q1 reports 1,000,000 shares worth $50 million, implying $50 per share. Q2 reports the same 1,000,000 shares worth $65 million, implying $65 per share. Reported value rose by $15 million, and price movement is sufficient to explain the difference. An unchanged quarter-end share count does not rule out offsetting purchases and sales during the quarter. A share-count change proves that the two reported snapshots differ, but 13F does not disclose the intervening trading path.
| Measure | Reproducible formula | Interpretation |
|---|---|---|
| Share change | Shares_t − Shares_t-1 | Change in reported quantity |
| Share change rate | (Shares_t ÷ Shares_t-1) − 1; prior shares must exceed zero | If prior shares are zero, label as new instead |
| Implied price | Value_USD ÷ Shares | Unit, split, and outlier check |
| Value change | Value_t − Value_t-1 | Affected by both shares and price |
Three sources of false trades: splits, amendments, and classes
A two-for-one stock split can turn one million shares into two million without any trade. Labeling that as a 100% purchase would be wrong; adjust the earlier share count for the corporate action before comparing economic exposure. Next, a 13F-HR/A amendment may restate an entire table or correct selected entries. Never add the original and amendment together. Read the amendment type and explanation, determine its scope, and construct one final effective snapshot for that period. Finally, one issuer can have Class A shares, Class B shares, preferred stock, convertible securities, or options. The SEC notes that multiple rows for an issuer may also reflect different security classes or types of investment discretion. Match primarily on CUSIP, security class, and the put/call flag instead of merging by issuer name alone.
A five-step workflow that another analyst can reproduce
💡 Source → period → unit → comparison → limitations
- Source: begin with the SEC EDGAR filing and record form type, accession number, CIK, and the original filing URL.
- Period: verify periodOfReport rather than relying on filedAt; check for later amendments and notice or combination reports involving another manager.
- Unit: determine whether the filing uses former thousands or current dollars; normalize to USD while preserving the raw value and unit.
- Comparison: match CUSIP, security class, and put/call status; process stock splits and other corporate actions before comparing shares, implied price, and value.
- Limitations: disclose the lag, official-list scope, possible confidential treatment, and the absence of trade dates and cost basis; keep every conclusion within those limits.
Keep a minimum audit record
Every published conclusion should trace back to the manager CIK, form type, accession number, reporting period, filing timestamp, amendment status, security identifier, raw shares, raw value, raw unit, normalized dollar value, corporate-action adjustment, and formula used. Perform three manual checks before publication: compare a sample against the SEC information table; divide value by shares to detect implausible magnitudes; and confirm that the original filing and its amendment were not counted twice. EDGAR acceptance confirms receipt, not substantive accuracy, so the underlying document still requires review.
Keep conclusions inside the evidence
Form 13F is most useful for producing verifiable clues about reported holdings changes, not unsupported return signals. A defensible statement is: “Quarter-end reported shares increased from the prior filing and still increased after split adjustment.” An indefensible leap is: “The manager turned bullish at quarter end, bought at the quarter-end price, and the stock will rise.” If the question requires complete AUM, cash, shorts, non-13(f) assets, exact trade timing, execution prices, or motive, obtain another primary source. This guide is for data-research education and is not investment advice.