Insider Trading and Market Abuse
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In short
The first thing to know is that there is no statute which says insider trading is illegal.
Scope. This article sets out the elements of the offence and what the rules require. It contains no account of what is or is not detected, no discussion of enforcement patterns, and no operational description of how any manipulative practice is carried out. Those omissions are deliberate and stated rather than concealed. The short-selling mechanics and the Regulation SHO requirements are in Short Selling and are not repeated. United States law, verified 17 August 2026; this is a summary of a contested area and is not legal advice.
Liability is built on Rule 10b-5, made under section 10(b) of the Securities Exchange Act — a general anti-fraud provision that does not mention insiders at all. Everything else has been developed by courts interpreting what fraud means in this setting, which is why the doctrine is intricate, why its edges are genuinely unsettled, and why intuitions about it are so often wrong.
What the offence actually requires
Trading while holding material non-public information is not, by itself, the offence. That single sentence corrects most of what circulates on this subject.
Because the rule is an anti-fraud rule, the conduct must be deceptive. And silence is only deceptive where there is a duty to speak. There are no duties to the world at large, so the duty has to come from somewhere — a pre-existing fiduciary relationship, or a comparable relationship of trust and confidence.
Liability also requires scienter — an intent to deceive, manipulate or defraud.
| Theory | Where the duty comes from |
|---|---|
| Classical | An insider trading in his own corporation's securities breaches a duty to, and takes advantage of, that corporation's shareholders |
| Misappropriation | A person who takes confidential information in breach of a duty owed to its source — the source need not be the company whose shares are traded |
| Misrepresentation | An actual false statement rather than silence. Rare, because most trading happens on impersonal markets where no representations are made to a counterparty. |
Tipping, and the requirement that surprises people
Most of the difficulty in this area concerns liability for trading on a tip rather than on one's own information.
The governing case established two conditions. A tippee is liable only if they know or should know that the tipper breached a duty by disclosing. And the tipper must have sought to personally benefit from the disclosure.
The benefit need not be money. It can be a quid pro quo, or a reputational gain, or a gift of information to a trading relative or friend — the reasoning being that a gift of information resembles the insider trading himself and then handing over the profits.
Worked example
The case itself illustrates how narrow the offence can be, and it is worth knowing. In the case that established the test, a former insider leaked information about corporate fraud to an analyst, who passed it to clients, who traded. The Court held there was no violation. The tipper had been motivated by a desire to expose the fraud rather than by any personal benefit — so there was no breach of duty, and therefore nothing for the tippee's liability to attach to. Information moved from an insider to traders who profited, and no offence was committed. That is not a loophole; it is what an anti-fraud rule does when there was no fraud.
One question remains genuinely open. Whether the personal-benefit requirement applies to tipping cases brought on the misappropriation theory was expressly not decided by the Supreme Court, and the lower courts have split on it. A reader should treat any confident statement on that point with caution, including a confident statement that it is settled.
Pre-arranged trading plans, and a reform that was measured
Corporate insiders frequently need to sell shares for reasons unconnected with what they know. Rule 10b5-1 provides a defence for trades made under a plan adopted while not in possession of material non-public information.
The rule was substantially amended in December 2022, introducing cooling-off periods between adopting a plan and trading under it.
| Who | Cooling-off period |
|---|---|
| Directors and officers of the issuer | The later of 90 days after adoption or modification, or two business days after the issuer discloses financial results for the quarter in which the plan was adopted or modified — capped at 120 days |
| All other persons | 30 days |
| Plans adopted by the issuer itself | None |
The amendments also banned overlapping plans, limited single-trade arrangements, required a certification that the insider does not hold material non-public information at adoption, and added disclosure about plan usage, terminations, gifts and option grants. A change to the amount, price or timing of trades counts as terminating the plan and adopting a new one — which starts a new cooling-off period.
What happened afterwards is unusual enough to be worth reporting, and it is reported as a finding rather than as an endorsement. Press analysis before the reform estimated that insiders trading within 60 days of adopting a plan had earned several hundred million dollars more than if they had waited three months — a press estimate, not a regulatory finding. Subsequent academic work examining behaviour after the amendment found that plan usage fell most sharply among the group most affected by the change: insiders who had previously traded within 90 days of adoption reduced their use of these plans by about 8.6 percentage points. And rather than moving those trades outside the plan structure, many appear to have curtailed the trading altogether. This is one of the few places in Group IV where a specific regulatory intervention has been measured and appears to have changed behaviour in the intended direction. The finding comes from a working paper and should be read with the weight appropriate to that. This portal expresses no view on whether the reform was desirable.
Market abuse more broadly
Insider trading is one offence within a wider category. The others share a structure: creating a false impression about supply, demand or price.
Wash trading — transactions that produce no change in beneficial ownership, generating apparent volume where no economic transfer occurred.
Spoofing — entering orders without the intention that they execute, so that the displayed order book misrepresents genuine interest.
Marking the close — transacting near a session's end to influence the price at which the day is recorded.
These are described here at the level of what they are, deliberately and not further. An account of how such conduct is arranged would be instruction rather than protection, which is the line this pillar draws. What connects them to the rest of this pillar is that each one damages the informational content of a price — the thing every article in Pillars 25 and 29 assumes a price has.
Frequently asked
8 questions
Is there a law that says insider trading is illegal?
Not a bespoke one. Liability is built on Rule 10b-5 under section 10(b) of the Securities Exchange Act — a general anti-fraud provision that does not mention insiders. The rest has been developed by courts, which is why the doctrine is intricate and its edges genuinely unsettled.
Is trading while holding inside information the offence?
Not by itself. Because the rule is an anti-fraud rule the conduct must be deceptive, and silence is only deceptive where there is a duty to speak. There are no duties to the world, so the duty must come from a fiduciary relationship or a comparable relationship of trust and confidence. Scienter is also required.
What are the theories of liability?
Classical, where an insider breaches a duty to his own corporation's shareholders; misappropriation, where a person takes confidential information in breach of a duty owed to its source, which need not be the company whose shares are traded; and misrepresentation, which is rare because impersonal markets involve no statements to a counterparty.
When is someone liable for trading on a tip?
Only if they know or should know the tipper breached a duty by disclosing, and the tipper sought to personally benefit. The benefit need not be money — a quid pro quo, a reputational gain, or a gift of information to a trading relative or friend can suffice.
Can information reach traders without any offence occurring?
Yes. In the case establishing the test, an insider leaked information about corporate fraud, an analyst passed it on, clients traded — and there was no violation, because the tipper was motivated by exposing the fraud rather than by personal benefit. That is not a loophole; it is what an anti-fraud rule does when there was no fraud.
Is anything about tipping unsettled?
Yes. Whether the personal-benefit requirement applies to tipping cases brought on the misappropriation theory was expressly not decided by the Supreme Court, and the lower courts have split. Treat confident statements either way with caution.
What are the cooling-off periods under Rule 10b5-1?
For directors and officers, the later of 90 days after adoption or modification or two business days after the issuer discloses results for the quarter in which the plan was adopted or modified, capped at 120 days. For all other persons, 30 days. Issuer plans have none. A change to amount, price or timing terminates the plan and starts a new period.
Did the 2022 reform work?
Academic work found plan usage fell most among the group most affected — insiders who had previously traded within 90 days of adoption reduced use by about 8.6 percentage points — and many appear to have curtailed the trading rather than moving it outside the plan structure. The finding comes from a working paper and should be read accordingly.
References
- SEC — Insider Trading Arrangements and Related Disclosures, adopting release 33-11138 (December 2022): the Rule 10b5-1 cooling-off periods, certification and disclosure amendments —
- SEC — proposing release 33-11013 (January 2022): background on scienter and the classical and misappropriation theories —
- Congressional Research Service — tippee liability, the personal benefit requirement and its development —
- Columbia Law School Blue Sky Blog — Insider trading after the 2022 Rule 10b5-1 amendment: the working-paper evidence on the response —
- University of Chicago Business Law Review — Insider abstention and Rule 10b5-1 plans (duty to speak and the limits of silence as deception) —
Educational and informational only — not investment advice, a recommendation, or an offer to buy or sell any security. Investing involves risk, including the possible loss of principal. Worked examples use fictional companies and figures.