Trading Activity

Open Market Purchase

By InsiderAlpha Research · Reviewed August 3, 2026

A reported insider purchase identified by Code P, which the SEC defines as an open-market or private purchase.

Definition

On Form 4, transaction code P identifies an open-market or private purchase of a non-derivative or derivative security. Analysts use it to separate reported purchases from grants, option exercises, gifts, and other acquisitions, then read the price and footnotes to determine venue and terms.

Code P is the strongest starting point for identifying capital deployed by an insider, but the SEC definition is broader than the term's common shorthand: P means an open-market or private purchase. Price, footnotes, ownership form, and remaining holdings determine how confidently a record can be described as a public-market conviction buy.

Related Form 4 codes

POpen-market or private purchaseAGrant, award, or other acquisitionMExercise or conversion of derivative

What Code P Establishes

The SEC's Form 4 instructions define Code P as an open-market or private purchase of a non-derivative or derivative security. A Code P record therefore establishes that the filer reported a purchase; it does not by itself establish that the order executed on a stock exchange, used only personal cash, or expressed a view that the shares were undervalued.

That distinction matters for editorial accuracy. The transaction price and filing footnotes can identify a negotiated or private purchase. The reported ownership form—direct or indirect—shows whose account holds the securities, while shares_owned_after puts the acquisition in the context of the position that remains.

How It Appears in InsiderAlpha Data

Start with Type = P. Then inspect Shares, Price, Total_Value, Date, security_title, acquired_disposed = A, shares_owned_after, and ownership_nature. Use accession_number to return to EDGAR and read Notes before labeling the purchase as exchange-traded.

Nominal value is generally Shares × Price. It measures transaction size, not conviction by itself. A useful review compares the dollar amount with the insider's role, prior trades, post-transaction holdings, and whether other insiders bought in the same period.

Real Dataset Example

White Mountains director Raymond Joseph Rene Barrette reported a December 17, 2012 Code P acquisition of 1,000 common shares at $519, a nominal value of $519,000. The sample's footnote says “Private purchase.” That single phrase prevents an incorrect claim that the trade executed on an exchange. The record reports direct ownership and 17,966 shares owned after the transaction; SEC accession 0001327330-12-000032 provides the source trail.

Common Analytical Errors

Error 1: expanding P as only “open-market purchase.” The official code includes private purchases.

Error 2: counting Code A or M as comparable buying. Grants and option exercises can increase shares without the same capital-at-risk decision.

Error 3: treating any P as proof of future appreciation. A purchase is evidence of behavior, not a forecast.

Error 4: ignoring amendments and duplicate rows. Use accession, transaction sequence, amendment, current-record, and supersession fields to avoid double counting.

Purchase-Like Form 4 Codes

CodeSEC CategoryEditorial Treatment
POpen-market or private purchasePotential capital-at-risk signal; verify venue, price, footnotes, and ownership context.
AGrant, award, or other acquisitionUsually compensation or another non-market acquisition, not a voluntary purchase.
MExercise or conversion of derivativeAnalyze the paired derivative table and any subsequent sale; do not classify as P.
GGiftChanges ownership but normally does not represent an arm's-length purchase.

Primary Sources & Filing References

Live Insider Data

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Why it matters for Whale Tracking

Code P is useful evidence that a reporting person acquired securities through a purchase rather than compensation mechanics. Its weight depends on transaction size, insider role, ownership form, post-transaction holdings, purchase terms, and the broader pattern of filings.

Technical Nuance

The phrase 'open-market purchase' is common shorthand, but Code P also covers private purchases. A reliable pipeline should preserve footnotes, amendments, accession lineage, ownership nature, and transaction sequence before presenting a trade as a public-exchange conviction buy.

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Real-World Example

"A White Mountains director reported a 2012 Code P acquisition of 1,000 shares at $519. The filing footnote says 'Private purchase,' demonstrating why Code P alone does not establish that a transaction occurred on an exchange."

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Open Market Purchase — Frequently Asked Questions

>Does Code P always mean an exchange purchase?

No. The SEC defines P as an open-market or private purchase. Review the price and footnotes before describing the venue.

>Is every Code P transaction bullish?

No. Code P is useful behavioral evidence, but size, role, post-transaction ownership, purchase terms, and the broader filing pattern determine its analytical weight.

>Why exclude Code M from purchase volume?

Code M is an option exercise or derivative conversion at contractual terms, not the same decision as purchasing shares at the current market or negotiated price.