Insider Trading Definition: What It Means and How It Is Reported

Insider trading means buying or selling a company's securities while in possession of material, nonpublic information about that company. The term covers both legal activity, such as an executive buying shares through a pre-cleared plan, and illegal activity, where someone trades (or tips someone else to trade) in breach of a duty owed to the source of the information.

What "insider trading" actually means

There is no single statutory definition of insider trading in US law. Congress never wrote one into the Securities Exchange Act of 1934. Instead, the prohibition comes from the SEC's general antifraud rule, Rule 10b-5 (17 CFR 240.10b-5), adopted under Section 10(b) of the Exchange Act, and from decades of court decisions applying it to trading on confidential information.

Two elements run through nearly every insider trading case:

• Material, nonpublic information: information a reasonable investor would consider important to an investment decision, and that has not yet been disclosed to the market.
• A breach of duty: trading (or tipping) in violation of a duty of trust or confidence, either owed directly to the company and its shareholders (the "classical" theory) or owed to the source of the information, such as an employer, even if that source is not the company whose stock is traded (the "misappropriation" theory, confirmed by the Supreme Court in United States v. O'Hagan, 1997).

Trading on material nonpublic information without a breach of duty is not automatically illegal under this framework, which is why insider trading is better understood as a legal test applied to a trade, not a fixed category of transaction.

Legal insider trading vs illegal insider trading

Officers, directors and large shareholders buy and sell their own company's stock all the time, and most of it is completely legal. It becomes illegal insider trading when the person traded (or tipped) while possessing material nonpublic information in breach of a duty. A few markers separate the two in practice:

The rules that define the boundary

A handful of SEC rules do the actual legal work behind the term:

• Rule 10b-5 is the core antifraud rule. It does not mention insider trading by name; courts and the SEC have applied its broad prohibition on fraud "in connection with the purchase or sale of any security" to trading on material nonpublic information.
• Section 16 of the Exchange Act applies specifically to officers, directors and beneficial owners of more than 10% of a company's registered equity. It has three parts: Section 16(a) requires these insiders to report their transactions (Forms 3, 4 and 5); Section 16(b) lets the company recover "short-swing" profits from any purchase and sale, or sale and purchase, within six months, regardless of intent; Section 16(c) bars these insiders from short selling the company's stock.
• Rule 10b5-1 gives insiders a way to trade on a pre-set schedule or formula, adopted at a time when they are not aware of material nonpublic information, as an affirmative defense against an insider trading claim for those specific trades.

How the SEC's own data marks a trade as pre-planned

In December 2022, the SEC adopted amendments to Rule 10b5-1 in Release No. 33-11138, "Insider Trading Arrangements and Related Disclosures." Along with new cooling-off periods before a 10b5-1 plan can start trading (90 days for most officers and directors, up to 120 days depending on when the next periodic report is filed, 30 days for everyone else covered by the rule), the amendments added a checkbox to Form 4: filers now mark whether a reported transaction was made under a Rule 10b5-1 trading arrangement.

Who has to report, and on what form

Form 4 transaction codes tell you what kind of event occurred: P for an open market purchase, S for an open market sale, A for a grant or award, M for an option exercise, and others. SEC Form 4 explained covers the full code list and how to read a single filing.

Reading insider trading data without guessing

Insider trading data, on its own, only shows what an insider did: the security, the transaction code, the price, the shares, the date and, since 2023, whether a Rule 10b5-1 plan covered it. It does not show what information the insider had, so treat it as a record of activity, not evidence of wrongdoing or a signal to copy.

SecFeed parses every Form 3, 4 and 5 into structured rows, including the 10b5-1 flag and the code-value transaction type, so you can filter insider activity without downloading and parsing individual XML filings. For example, open market purchases over $100,000:

curl "https://secfeedapi.com/v1/insider-trading?code=P&minValue=100000" \
  -H "Authorization: Bearer YOUR_API_KEY"

from secfeed import Client

sf = Client("YOUR_API_KEY")
purchases = sf.insider_trades(code="P", minValue=100000)
for t in purchases["data"][:10]:
    print(t["issuer"], t["owner"], t["shares"], t["price"])

Full parameters, including filtering by owner, role and date range, are at /docs/#v1-insider-trading. To watch for related filings before a sale, such as a Form 144 notice of a proposed sale of restricted stock, see Form 144 explained, and for a worked example filtering one company's full insider history, see insider trading analysis for one company.

Frequently asked questions

Is insider trading always illegal?

No. Trading by an officer, director or employee of their own company's stock is legal as long as it is not based on material nonpublic information, or is made under a properly adopted Rule 10b5-1 trading plan. It becomes illegal when the trade (or a tip leading to a trade) breaches a duty of trust tied to material nonpublic information.

What counts as "material" information?

Information is generally considered material if there is a substantial likelihood that a reasonable investor would consider it important to an investment decision, or that it would significantly alter the total mix of information available about a company. There is no fixed list of material events; it depends on the facts.

How does the SEC find out about insider trading?

Legal insider transactions are self-reported on Forms 3, 4 and 5, which become public on EDGAR. Illegal insider trading is typically uncovered through market surveillance for unusual trading ahead of news, tips, and referrals, then investigated by SEC Enforcement, which can bring civil claims and refer matters for criminal prosecution.

What is a Rule 10b5-1 trading plan?

It is a written plan, adopted when the insider is not aware of material nonpublic information, that sets a schedule or formula for future trades. Trades executed under a plan that meets the rule's conditions, including the cooling-off periods added in the SEC's 2022 amendments, can serve as an affirmative defense against an insider trading claim for those specific trades.

Does Section 16 cover every employee with inside information?

No. Section 16 applies specifically to a company's officers, directors and beneficial owners of more than 10% of its registered equity securities. Other employees who trade on material nonpublic information can still violate Rule 10b-5, but they are not subject to Section 16's separate reporting and short-swing profit rules.