SEC Form 4 transaction code

Form 4 Code S: Open Market or Private Sale

Code S marks a sale of the company’s stock, or of a derivative, in the open market or in a private transaction.

“Open market or private sale of non-derivative or derivative security”

SEC Form 4, General Instruction 8 (Transaction Codes), under “General Transaction Codes”. Form 4 and instructions (PDF, sec.gov)

How often code S appears in real filings

Share of transaction rows

38.3%

23,020 of 60,072 rows, 1st most common

Filings with a code S row

35.0%

8,367 of 23,939 filings

Companies

1,472

of 2,158 in the sample

Median days, trade to filing

calendar days

22,630 of the rows are in Table I (non-derivative securities) and 390 in Table II (derivative securities). 65.5% of code S rows are on filings with the Rule 10b5-1 plan box checked.

Sample: 60,072 transaction rows in 23,939 Form 4 and 4/A filings filed Jul 23 – Nov 10, 2026 by insiders of 2,158 companies with an AlphaScala stock page. Rows are counted as filed; see how the codes are counted.

SEC Form 4 filings as of Nov 10, 2026

Reading code S on a Form 4

Many sales follow an exercise or a vesting reported on the same Form 4. An executive exercises options (code M) and sells some or all of the new shares the same day, or sells shares that have just vested. The filing shows both legs, so the sale can be read against what was received and what is left.

Since April 2023 Form 4 has a checkbox for transactions made under a contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). A sale on a filing with that box checked was scheduled under such a plan, and General Instruction 10 asks the filer to give the date the plan was adopted.

Not every disposal is a sale. Shares the company withholds to pay tax on vesting are code F, gifts are code G, shares handed back to the company are code D and shares tendered into a takeover offer are code U. Counting those rows as sales overstates insider selling, and AlphaScala’s insider tables count only code S as a sale.

Code S in real filings

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

ALLALLSTATE CORP

Filing on sec.gov

Insider: WILSON THOMAS J, Chairman, President & CEO
Transaction date: Nov 6, 2026
Filed: Nov 10, 2026
Table: I, non-derivative
Shares: 35,200
Price: $260.10
Shares × price: $9.2M
Held after: 80,815 (indirect)

WILSON THOMAS J (Chairman, President & CEO) sold 35,200 shares at $260.10 per share, about $9.2M.
Shares held after the transaction: 80,815, held indirectly (By TJW Options LLC 2017 Series).
The same filing also reports 4 code M rows (496,894 shares and derivative securities), 2 code F rows (74,453 shares) and 2 code S rows (7,877 shares).
Filed 4 days after the transaction date.

ANETArista Networks, Inc.

Filing on sec.gov

Insider: BECHTOLSHEIM ANDREAS, 10%+ Owner
Transaction date: Nov 6, 2026
Filed: Nov 10, 2026
Table: I, non-derivative
Shares: 88,958
Price: $167.74
Shares × price: $14.9M
Held after: 179,926,198 (indirect)

BECHTOLSHEIM ANDREAS (10%+ Owner) sold 88,958 shares at $167.74 per share, about $14.9M.
Shares held after the transaction: 179,926,198, held indirectly (by Trust).
The Rule 10b5-1 box is checked on this filing: a transaction on it was made under a plan intended to meet Rule 10b5-1(c).
The same filing also reports 5 code S rows (171,042 shares).
Filed 4 days after the transaction date.

CRBGCorebridge Financial, Inc.

Filing on sec.gov

Insider: Argon Holdco LLC, 10%+ Owner
Transaction date: Nov 6, 2026
Filed: Nov 10, 2026
Table: I, non-derivative
Shares: 3,227,700
Price: $34.09
Shares × price: $110.0M
Held after: 44,234,423 (indirect)

Argon Holdco LLC (10%+ Owner) sold 3,227,700 shares at $34.09 per share, about $110.0M.
Shares held after the transaction: 44,234,423, held indirectly (See Footnotes).
Filed 4 days after the transaction date.

Codes read alongside S

Code F: Shares withheld for tax or exercise price – shares withheld for tax, which is not a sale
Code M: Exempt exercise or conversion – the option exercise that often precedes a sale
Code P: Open market or private purchase – the purchase side of the same definition
Code G: Bona fide gift – gifts, which reduce holdings without a sale

Questions about these codes

How common is code S on Form 4?

In AlphaScala’s sample of 60,072 Form 4 transaction rows filed Jul 23 – Nov 10, 2026, code S made up 38.3% of rows (23,020) and appeared on 35.0% of filings (8,367 of 23,939). It was the 1st most common of the 18 codes found.

Is code S the same as code F?

No. S is a sale in the open market or in a private transaction. F is "payment of exercise price or tax liability by delivering or withholding securities" tied to a Rule 16b-3 award: the company keeps shares to cover the tax or exercise price, and the insider does not sell them in the market.

What does the 10b5-1 box mean on a code S sale?

The filer checks it to indicate that a transaction on the form "was made pursuant to a contract, instruction or written plan" intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). The box has been on Form 4 since April 2023, and the filer gives the plan’s adoption date in the explanation of responses.

Why do insiders sell stock?

Form 4 does not ask. Sales can pay tax on vested stock, fund an option exercise, diversify a concentrated holding or carry out a plan adopted months earlier. The filing shows the size and price of the sale and the holdings left afterwards, and footnotes sometimes add context.

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.