Section 16 Transaction Codes: The 2026 Complete Guide for Compliance Officers
Section 16 transaction codes are the alphabetic identifiers the SEC requires insiders to enter on every Form 4 and Form 5 filed via EDGAR. Get one wrong and you risk mischaracterizing an exempt transaction as non-exempt, triggering unnecessary short-swing profit exposure, or attracting an SEC comment letter. The SEC's official code list gives you the labels; this guide gives you the legal consequence behind each one.
This article is for corporate secretaries, general counsel, and compliance officers at Exchange Act-reporting companies who prepare or review Section 16 filings. If you need a broader primer on who files and when, see Finrep's Section 16 Insider Reporting Compliance Guide 2026.
Key takeaway: There are 20 distinct transaction codes organized across five categories. Choosing the right one is not cosmetic: the code determines whether a transaction is subject to Section 16(b) short-swing profit disgorgement, and EDGAR will accept any valid code regardless of whether it matches the actual transaction.
What Are Section 16 Transaction Codes?
Section 16 transaction codes are standardized alphabetic identifiers that classify the nature of each ownership change reported on Forms 4 and 5. They appear in the Transaction Code column of Table I (non-derivative securities) and Table II (derivative securities). The code field is mandatory on both forms.
Section 16(a) of the Securities Exchange Act of 1934 requires directors, officers, and beneficial owners of more than 10% of a registered class of equity securities to report changes in beneficial ownership. Section 16(b) then imposes strict liability for short-swing profits, defined as any profit from a purchase and sale (or sale and purchase) of the issuer's equity within any six-month period. The transaction code is the mechanism that tells the SEC, the issuer, and the public whether a given transaction falls inside or outside that liability.
The SEC publishes the authoritative code list at sec.gov. There are exactly 20 codes, split across five logical categories.
The Five Categories of Form 4 Transaction Codes
Category 1: General Transaction Codes (P, S, V)
These three codes cover the most common open-market activity.
| Code | Meaning | 16(b) Exempt? |
|---|---|---|
| P | Open market or private purchase of non-derivative or derivative security | No |
| S | Open market or private sale of non-derivative or derivative security | No |
| V | Transaction voluntarily reported earlier than required | Modifier only |
P and S are the workhorses of Form 4 reporting, and neither is exempt from Section 16(b). An open-market purchase followed by an open-market sale within six months is the textbook short-swing profit scenario. Code V is not a standalone transaction code; it is a modifier (covered in detail below).
A common error: compliance teams sometimes code an RSU vesting event as P, as if the insider "purchased" shares. That is wrong. RSU vesting under a Rule 16b-3-compliant plan is code M (or code F for the tax-withholding leg). Using P on a vesting event misrepresents an exempt transaction as a non-exempt one and creates phantom short-swing profit exposure.
Category 2: Rule 16b-3 Transaction Codes (A, D, F, I, M)
Rule 16b-3 exempts certain transactions between an issuer and its officers or directors from Section 16(b) liability, provided the transaction meets the rule's conditions (typically board, compensation committee, or shareholder approval). Codes A, D, F, I, and M all correspond to Rule 16b-3-exempt transactions.
| Code | Meaning | Underlying Rule | Common Example |
|---|---|---|---|
| A | Grant, award, or other acquisition pursuant to Rule 16b-3(d) | Rule 16b-3(d) | RSU grant, stock option grant, restricted stock award |
| D | Disposition to the issuer pursuant to Rule 16b-3(e) | Rule 16b-3(e) | Share repurchase by the issuer from the insider |
| F | Payment of exercise price or tax liability by delivering or withholding securities incident to receipt, exercise, or vesting under Rule 16b-3 | Rule 16b-3 | Tax withholding on RSU vesting (net settlement) |
| I | Discretionary transaction under Rule 16b-3(f) resulting in acquisition or disposition | Rule 16b-3(f) | Reallocation within a company benefit plan |
| M | Exercise or conversion of derivative security exempted pursuant to Rule 16b-3 | Rule 16b-3 | Stock option exercise under a board-approved plan |
Critical point: The exemption belongs to the transaction, not the code. Using code A for a grant that was not properly approved by the board or compensation committee does not create a Rule 16b-3 exemption. The code reflects the legal status; it does not manufacture it.
Code F deserves special attention. When an insider vests RSUs and the company withholds shares to cover the tax liability (net settlement), two codes appear on the same Form 4: code M for the vesting/acquisition, and code F for the disposition of the withheld shares. Both are Rule 16b-3-exempt. Filing only one of these, or coding the withholding as S (an open-market sale), is a frequent error that overstates the insider's dispositions and can generate incorrect short-swing profit analyses.
Code M vs. codes O and X: This distinction carries direct 16(b) consequences. Code M applies when the derivative exercise is exempt under Rule 16b-3 (e.g., an option exercise under a board-approved plan). If the exercise is not Rule 16b-3-exempt, use code O (out-of-the-money exercise) or code X (in-the-money or at-the-money exercise) instead. Those codes sit in Category 3 and are not exempt from Section 16(b).
Category 3: Derivative Securities Codes (C, E, H, O, X)
These codes apply to derivative transactions that are NOT exempted under Rule 16b-3.
| Code | Meaning | 16(b) Exempt? |
|---|---|---|
| C | Conversion of derivative security | No |
| E | Expiration of short derivative position | No |
| H | Expiration (or cancellation) of long derivative position with value received | No |
| O | Exercise of out-of-the-money derivative security | No |
| X | Exercise of in-the-money or at-the-money derivative security | No |
None of these codes confer a Section 16(b) exemption. The O/X distinction matters because in-the-money exercises (X) are more likely to attract short-swing profit analysis when paired with a prior sale within six months. Practitioners sometimes use M when they should use X, effectively claiming a Rule 16b-3 exemption that does not apply. That is a misrepresentation on a public filing.
Category 4: Other Section 16(b) Exempt and Small Acquisition Codes (G, L, W, Z)
These codes cover transactions that are exempt from Section 16(b) for reasons other than Rule 16b-3.
| Code | Meaning | Exemption Basis | Notes |
|---|---|---|---|
| G | Bona fide gift | Exempt by rule | Must be a genuine gift; no consideration received |
| L | Small acquisition under Rule 16a-6 | Rule 16a-6 | Market value under $10,000 in any six-month period |
| W | Acquisition or disposition by will or laws of descent and distribution | Exempt by rule | Inheritance, bequest |
| Z | Deposit into or withdrawal from voting trust | Exempt by rule | No change in economic interest |
Code L and the $10,000 threshold: Rule 16a-6 exempts acquisitions with a market value of less than $10,000 during any six-month period from Section 16(b) liability. Compliance teams must track cumulative acquisition value across the period; once the threshold is crossed, the exemption is lost for that period.
Code G (gift) is genuinely exempt from Section 16(b), but the gift must be bona fide. A purported gift that is actually a disguised sale will not qualify, and SEC staff have scrutinized gift claims in enforcement contexts.
Category 5: Other Transaction Codes (J, K, U)
| Code | Meaning | 16(b) Exempt? | Notes |
|---|---|---|---|
| J | Other acquisition or disposition (describe in Remarks) | Depends on transaction | Catch-all; requires Remarks description |
| K | Transaction in equity swap or instrument with similar characteristics | Modifier only | Appended to primary code |
| U | Disposition pursuant to a tender of shares in a change of control transaction | Depends on transaction | Tender offer context |
Code J is a catch-all, not a default. It should only be used when no other code accurately describes the transaction. Overuse of J, particularly when a more specific code exists, is a compliance red flag. SEC staff reviewing EDGAR filings notice patterns of J-code overuse and may issue comment letters requesting clarification. Always exhaust the specific codes before reaching for J.
Modifier Codes: V, K, and Delinquency Suffixes
Three codes function as modifiers rather than standalone transaction codes. This is the area most poorly documented in existing resources.
Code V: Voluntary Early Reporting
When an insider voluntarily reports a transaction before the mandatory deadline (most commonly, reporting a Form 5-eligible transaction early on a Form 4), code V must be used alongside the primary transaction code. As the Novaworks practitioner guide explains: "Transaction code 'V' should be placed in its own column for Table I and Table II, while the type of transaction being reported should have its code placed in the Transaction Code column."
Code V does not replace the primary code; it accompanies it in a separate column.
Code K: Equity Swap Modifier
Code K is appended to the primary transaction code when the transaction involves an equity swap or an instrument with similar characteristics. It is not used alone. For example, an equity swap that does not fit any specific category would be coded J/K, with a description in the Remarks field. Equity swaps are rare in Section 16 filings but face increasing enforcement scrutiny.
Delinquency Suffixes: 4 and 5
When reporting a transaction late, a numeric suffix is appended to the primary transaction code:
- Append 4 for transactions that should have been reported on a Form 4.
- Append 5 for transactions that should have been reported on a Form 5.
For example, a late-reported grant under Rule 16b-3(d) that should have appeared on a Form 4 uses code A4. This signals to the SEC and to the public that the transaction was not timely filed, which is itself a disclosure of non-compliance.
The Most Common Section 16 Transaction Code Errors
EDGAR accepts any valid code regardless of whether it matches the transaction. The compliance burden sits entirely with the filer and their counsel. These are the errors that appear most often in practice:
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Coding RSU vesting as P. RSU vesting under a Rule 16b-3-compliant plan is code M (acquisition) and, if shares are withheld for taxes, code F (disposition). Code P implies an open-market purchase and creates non-exempt short-swing profit exposure.
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Coding tax withholding on vesting as S. The net-settlement withholding of shares is code F, not S. Code S implies an open-market sale, which it is not, and generates a false disposition record.
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Using M when O or X is correct. Code M requires a Rule 16b-3 exemption. If the option or derivative exercise is not covered by Rule 16b-3, use O (out-of-the-money) or X (in-the-money or at-the-money). Using M without a valid exemption misrepresents the transaction's legal status.
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Defaulting to J when a specific code exists. Code J is a last resort. Filing J when code A, M, or F would be accurate invites SEC staff scrutiny and undermines the transparency Section 16 is designed to provide.
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Omitting the K modifier on equity swaps. Equity swap transactions require the K modifier appended to the primary code. Missing it is a technical filing deficiency.
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Missing the two-business-day window. Rule 16a-3 requires Form 4 to be filed before the end of the second business day following the transaction execution date. A filing that misses this window requires a delinquency suffix and creates a public record of late reporting. Building a pre-clearance and filing workflow that includes code selection as a step, not an afterthought, is the operational fix.
Quick-Reference Table: All 20 Section 16 Transaction Codes
| Code | Plain-English Meaning | 16(b) Exempt? | Underlying Rule/Basis | Common Example |
|---|---|---|---|---|
| P | Open-market or private purchase | No | Section 16(a) | Insider buys shares on Nasdaq |
| S | Open-market or private sale | No | Section 16(a) | Insider sells shares on NYSE |
| V | Voluntary early reporting (modifier) | N/A | Rule 16a-3 | Form 5 transaction reported early on Form 4 |
| A | Grant/award under Rule 16b-3(d) | Yes (if conditions met) | Rule 16b-3(d) | RSU grant, stock option grant |
| D | Disposition to issuer under Rule 16b-3(e) | Yes (if conditions met) | Rule 16b-3(e) | Issuer repurchases shares from officer |
| F | Tax/exercise price paid by share withholding under Rule 16b-3 | Yes (if conditions met) | Rule 16b-3 | Net settlement of RSU vesting |
| I | Discretionary transaction under Rule 16b-3(f) | Yes (if conditions met) | Rule 16b-3(f) | Plan reallocation |
| M | Derivative exercise exempt under Rule 16b-3 | Yes (if conditions met) | Rule 16b-3 | Stock option exercise under approved plan |
| C | Conversion of derivative (non-exempt) | No | Section 16(b) | Convertible note conversion |
| E | Expiration of short derivative position (non-exempt) | No | Section 16(b) | Short call expires worthless |
| H | Expiration/cancellation of long derivative with value received (non-exempt) | No | Section 16(b) | Long put cancelled for cash |
| O | Exercise of out-of-the-money derivative (non-exempt) | No | Section 16(b) | Out-of-the-money option exercise |
| X | Exercise of in-the-money or at-the-money derivative (non-exempt) | No | Section 16(b) | In-the-money option exercise outside plan |
| G | Bona fide gift | Yes | Exempt by rule | Insider gifts shares to family foundation |
| L | Small acquisition under Rule 16a-6 | Yes | Rule 16a-6 | Purchase under $10,000 in six-month period |
| W | Acquisition/disposition by will or descent | Yes | Exempt by rule | Inherited shares |
| Z | Deposit/withdrawal from voting trust | Yes | Exempt by rule | Shares placed in voting trust |
| J | Other (describe in Remarks) | Depends | Catch-all | Unusual transaction with no matching code |
| K | Equity swap modifier | N/A | Modifier | Appended to primary code: e.g., J/K |
| U | Tender in change of control | Depends | Tender offer rules | Shares tendered in acquisition |
Source: SEC EDGAR Ownership Form Codes.
FAQ: Section 16 Transaction Codes
What is the difference between code M and code X? Code M applies when a derivative security exercise is exempt under Rule 16b-3, typically because the underlying plan received board or compensation committee approval. Code X applies to in-the-money or at-the-money exercises that are not Rule 16b-3-exempt. Code X transactions are subject to Section 16(b) short-swing profit analysis; code M transactions are not (provided the exemption conditions are met).
Which code do I use for RSU vesting? Use code A for the initial grant. At vesting, use code M for the acquisition of shares (if the plan is Rule 16b-3-compliant) and code F for any shares withheld to cover the tax liability. Do not use code P.
Is code G (gift) really exempt from Section 16(b)? Yes, a bona fide gift is exempt. The gift must be genuine, with no consideration received. Gifts still require Form 4 reporting within the standard two-business-day window.
When should I use code J? Only when no other code accurately describes the transaction. Code J requires a description in the Remarks field. Using J when a specific code exists is a compliance error that can draw SEC staff attention.
What does appending '4' to a transaction code mean? It signals that the transaction is being reported late and should have appeared on a Form 4. For example, a late-reported grant uses code A4. The suffix creates a public record of the delinquency.
What is the Rule 16a-6 small acquisition threshold for code L? Acquisitions with a market value of less than $10,000 during any six-month period qualify under Rule 16a-6. Compliance teams must track cumulative value across the period; exceeding the threshold eliminates the exemption.
Does EDGAR validate that the transaction code matches the transaction? No. EDGAR accepts any valid code from the official list regardless of whether it accurately describes the transaction. The filer and their counsel bear full responsibility for correct code selection.
For the full framework on Section 16 filing obligations, deadlines, and the Form 3/4/5 distinctions, see Finrep's Form 3 vs Form 4 vs Form 5: 2026 SEC Insider Reporting Guide.
