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SEC Form 4 transaction code

Form 4 Code M: Option Exercise or Conversion

Code M marks the exercise or conversion of a derivative security, such as a stock option or restricted stock unit, that is exempt under Rule 16b-3, typically an award from the company’s own equity plans.

“Exercise or conversion of derivative security exempted pursuant to Rule 16b-3”
SEC Form 4, General Instruction 8 (Transaction Codes), under “Rule 16b-3 Transaction Codes”. Form 4 and instructions (PDF, sec.gov)

How often code M appears in real filings

Share of transaction rows
21.4%
12,407 of 57,980 rows, 2nd most common
Filings with a code M row
17.3%
4,017 of 23,238 filings
Companies
875
of 2,150 in the sample
Median days, trade to filing
2
calendar days

5,974 of the rows are in Table I (non-derivative securities) and 6,433 in Table II (derivative securities).

Sample: 57,980 transaction rows in 23,238 Form 4 and 4/A filings filed Jul 23 – Nov 6, 2026 by insiders of 2,150 companies with an AlphaScala stock page. Rows are counted as filed; see how the codes are counted.

SEC Form 4 filings as of Nov 6, 2026

Reading code M on a Form 4

One exercise usually fills two rows. General Instruction 4(c) says to "report the exercise or conversion of a derivative security in Table II (as a disposition of the derivative security)" and to report the underlying shares in Table I, and filers usually add a Table I M row for the shares received. That is why M rows split between the two tables in the statistics on this page.

An M row on its own is neither a purchase nor a sale. Many filings pair it with code S rows on the same day, an exercise-and-sell, or with code F rows, where shares are withheld to pay the exercise price or tax. Reading the whole filing shows how many of the new shares the insider kept.

The price on a Table I M row is normally the exercise price, not a market price, and restricted stock units convert at $0. Shares multiplied by that price is not a market value.

Code M in real filings

Recent Form 4 lines coded M, chosen from the newest filings in the sample, one company each. Figures are as filed; each links to the filing on sec.gov.

AXPAMERICAN EXPRESS CO

Filing on sec.gov
Insider
Squeri Stephen J, Chairman and CEO
Transaction date
Nov 4, 2026
Filed
Nov 6, 2026
Table
I, non-derivative
Shares
299,401
Price
$148.45
Shares × price
$44.4M
Held after
359,968 (direct)
  • Squeri Stephen J (Chairman and CEO) acquired 299,401 shares by exercising or converting a derivative security at $148.45 per share.
  • Shares held after the transaction: 359,968, held directly.
  • The same filing also reports 4 code S rows (299,401 shares) and 1 code M row (299,401 derivative securities).
  • Filed 2 days after the transaction date.

GDGENERAL DYNAMICS CORP

Filing on sec.gov
Insider
NOVAKOVIC PHEBE N, Chairman and CEO
Transaction date
Nov 3, 2026
Filed
Nov 5, 2026
Table
I, non-derivative
Shares
151,150
Price
$168.56
Shares × price
$25.5M
Held after
917,607 (direct)
  • NOVAKOVIC PHEBE N (Chairman and CEO) acquired 151,150 shares by exercising or converting a derivative security at $168.56 per share.
  • Shares held after the transaction: 917,607, held directly.
  • The same filing also reports 1 code F row (105,797 shares) and 1 code M row (151,150 derivative securities).
  • Filed 2 days after the transaction date.

WRBYWarby Parker Inc.

Filing on sec.gov
Insider
Blumenthal Neil Harris, Co-Chief Executive Officer
Transaction date
Nov 3, 2026
Filed
Nov 5, 2026
Table
II, derivative
Units
310,759
Price
$0.00
Shares × price
–
Held after
0 (direct)
  • Blumenthal Neil Harris (Co-Chief Executive Officer) exercised or converted 310,759 derivative securities; this is the Table II side of the exercise.
  • Derivative securities of this kind held after the transaction: 0, held directly.
  • The same filing also reports 1 code M row (310,759 derivative securities).
  • Filed 2 days after the transaction date.

Codes read alongside M

Questions about these codes

How common is code M on Form 4?

In AlphaScala’s sample of 57,980 Form 4 transaction rows filed Jul 23 – Nov 6, 2026, code M made up 21.4% of rows (12,407) and appeared on 17.3% of filings (4,017 of 23,238). It was the 2nd most common of the 16 codes found.

What is the difference between code M and code X?

Both are exercises. M is an "exercise or conversion of derivative security exempted pursuant to Rule 16b-3", which covers options and units from the company’s own plans. X is an "exercise of in-the-money or at-the-money derivative security" outside Rule 16b-3, for example warrants or options acquired some other way. Out-of-the-money exercises outside Rule 16b-3 are code O.

Does code M mean the insider sold shares?

No. M records the exercise or conversion. A sale of the shares received is reported separately with code S, often on the same Form 4, and shares withheld to pay the exercise price or tax are code F.

Why does a code M row show a price of $0?

Restricted stock units have no exercise price, so their conversion into shares is reported at $0. For stock options the price is the exercise price set when the option was granted.

Definition: SEC Form 4, General Instruction 8 (sec.gov). Examples and counts: AlphaScala's copy of SEC EDGAR Form 4 filings. See all 20 Form 4 transaction codes, insider cluster buys and our methodology.

Educational reference only, not investment advice. Insider transactions have many motives and a Form 4 does not record them. See our risk disclaimer.