What Is the Classical Theory of Insider Trading?

The classical theory of insider trading is the doctrine that corporate insiders violate federal securities law when they trade their own company’s stock while holding material nonpublic information, because doing so breaches the fiduciary duty they owe to that company’s shareholders. It rests on Section 10(b) of the Securities Exchange Act of 1934 and Rule 10b-5, which prohibit deceptive conduct in securities transactions.¹ The Supreme Court set out the framework in Chiarella v. United States (1980), holding that possessing confidential information is not itself illegal. What matters is whether the trader broke a relationship of trust.²

The Fiduciary Duty at the Core

Everything in the classical theory turns on one question: did the person who traded owe a fiduciary duty to the shareholders on the other side of the trade? A fiduciary duty is the legal obligation to act in someone else’s interest rather than your own. Corporate officers, directors, and certain employees carry that obligation because shareholders have entrusted them with running the business. When one of those insiders trades on confidential information, the law treats it as a deceptive act, because the insider is exploiting the very people they are supposed to protect.

Before Chiarella, prosecutors sometimes argued that anyone with an information advantage over other traders was committing fraud. The Supreme Court rejected that idea. The Court held that “a duty to disclose under § 10(b) does not arise from the mere possession of nonpublic market information” and that liability requires “a relationship of trust and confidence between parties to a transaction.”² A stranger who overhears merger talk at a restaurant is not covered by the classical theory. The theory only reaches people who owe a duty to the company’s shareholders.

Who Counts as an Insider

The obvious insiders are a company’s officers, directors, and large shareholders. They handle sensitive corporate data as part of their daily work, and their fiduciary duties are well established.

The category is broader than the boardroom, though. Outsiders who temporarily work for a company can inherit the same obligations. Accountants conducting an audit, lawyers handling a merger, and investment bankers underwriting a stock offering all receive confidential information for a narrow corporate purpose. Because the company shared that information in confidence, these professionals take on a fiduciary duty for the duration of the engagement. If a lawyer reviewing an acquisition file quietly buys stock in the target, the classical theory treats that trade the same as if the CEO had done it.

What Counts as Material Nonpublic Information

A trade only violates the classical theory if the insider held information that is both material and nonpublic. These are separate requirements, and both must be met.

Information is material if a reasonable investor would consider it important when deciding whether to buy, sell, or hold. The Supreme Court frames this as whether the fact would “significantly alter the total mix of information” available to investors.³ Pending mergers, earnings that beat or miss forecasts, major regulatory approvals, and executive departures routinely clear that bar. Materiality is judged from the perspective of the reasonable investor, not the insider.

Information is nonpublic until the company has disclosed it through official channels and the market has had a reasonable window to absorb it. A press release or SEC filing usually accomplishes this, but the information does not become “public” the instant it hits the wire. Insiders are expected to wait until the broader market has actually had a chance to process the news. A few people hearing a rumor at a conference does not make the information public.

Disclose or Abstain

An insider holding material nonpublic information faces a binary choice. Disclose the information publicly before trading, or don’t trade at all. There is no middle path.

For nearly all insiders, disclosure is not a real option. Employment agreements and corporate confidentiality policies forbid employees from revealing sensitive information on their own. Leaking upcoming earnings or merger details to justify a personal trade would breach those agreements and likely end the insider’s employment. The disclose-or-abstain rule therefore functions almost entirely as an abstain rule.

When Awareness Alone Triggers Liability

A recurring question is whether prosecutors must prove that an insider traded because of confidential information, or only that the insider traded while aware of it. The SEC settled this in favor of the awareness standard. Under Rule 10b5-1, a trade is made “on the basis of” material nonpublic information whenever the person executing the trade was aware of that information at the time.⁴

This matters more than it might seem. An insider who genuinely planned to sell stock for personal reasons can still face liability if, at the moment of the sale, they happened to know about an upcoming earnings miss. The government does not need to prove the news motivated the trade. Awareness is enough.

Rule 10b5-1 Trading Plans

Rule 10b5-1 offers an affirmative defense for insiders who set up a written trading plan before they learn any material nonpublic information. The logic is straightforward. If you locked in a plan to sell shares on a specific date at a specific price while you were still in the dark, the eventual trade reflects a pre-commitment rather than an exploitation of inside knowledge.

To qualify, the plan must meet several conditions:⁴

The insider must create the plan before becoming aware of any material nonpublic information, and must adopt it in good faith rather than as a way to evade the rules.
The plan must lock in the amount, price, and date of each trade, or use a written formula or algorithm that removes the insider’s discretion.
After adopting the plan, the insider cannot exercise any influence over how, when, or whether trades actually execute.

Directors and officers face additional requirements. They must certify in writing that they are not aware of any material nonpublic information when they adopt the plan and that they are acting in good faith.⁵ They also cannot begin trading under the plan until a cooling-off period expires. That period runs until the later of 90 days after plan adoption or two business days after the company files its next quarterly or annual financial results, capped at 120 days.⁴ Insiders who are not officers or directors face a shorter 30-day cooling-off period.

The SEC also restricts overlapping or single-trade plans. An insider generally cannot maintain multiple active plans that qualify for the defense, and someone who sets up a plan designed for one transaction cannot adopt another single-trade plan for 12 months. These guardrails exist because regulators grew concerned that some insiders were gaming the system by adopting, canceling, and re-adopting plans to time trades around inside knowledge.

How the Theory Reaches Tippers and Tippees

The classical theory does not stop with the insider who trades. It also reaches insiders who pass tips and the recipients who trade on them. The Supreme Court set out the framework in Dirks v. SEC (1983), which established two requirements for tippee liability.

First, the insider who shared the information (the tipper) must have breached a fiduciary duty by doing so, and that breach requires a “personal benefit” to the tipper. The benefit does not need to be cash. The Supreme Court confirmed in Salman v. United States (2016) that giving a tip to a relative or close friend as a gift satisfies the personal benefit test. Second, the person who received the tip (the tippee) must have known the insider was breaching a duty. A tippee who genuinely had no idea the information came from an insider’s breach does not face liability under this framework.

Chains of tippers complicate matters. If an insider tips a friend, who tips a colleague, who tips a trading partner, proving what the most remote tippee knew about the original breach gets difficult. Courts have not fully resolved how far down the chain the government must trace knowledge, and this remains one of the more actively litigated edges of insider trading law.

Where the Classical Theory Stops

The classical theory has a significant blind spot: it only covers people who owe a fiduciary duty to the company whose stock is being traded. Suppose a lawyer at an outside firm learns her client plans to acquire Company A, but instead of trading Company A’s stock, she trades stock in Company B, the target. She has no fiduciary relationship with Company B’s shareholders, so the classical theory does not reach her trade.

The misappropriation theory fills that gap. Recognized by the Supreme Court in United States v. O’Hagan (1997), it holds that a person who trades using confidential information stolen from the source of that information can be held liable, even without any duty to the company whose stock was traded. The Court described this conduct as “akin to embezzlement,” reasoning that the source of the information has an exclusive right to it and the trader effectively stole that right by trading without disclosure.⁶

The practical difference is the direction of the duty. Under the classical theory, the duty runs from the insider to the shareholders of the traded company. Under misappropriation, the duty runs from the trader to whoever entrusted them with the confidential information. Both theories operate under Rule 10b-5, but they cover different relationships. Most modern insider trading prosecutions plead both as alternative grounds when the facts support it.

What Prosecutors Must Prove and What’s at Stake

To win a conviction or civil judgment under the classical theory, the government must show that the trader held material nonpublic information, owed a fiduciary duty to the shareholders of the traded company, and executed a trade while aware of that information. The government must also establish scienter: a mental state showing the defendant intended to deceive or acted with reckless disregard for the law. An accidental trade, or one made by someone who genuinely did not understand the information’s significance, falls short.

The consequences are severe. An individual convicted of a willful violation of the Securities Exchange Act faces a fine of up to $5 million and as many as 20 years in prison. For corporations and other entities, the maximum fine rises to $25 million.⁷ Civil enforcement, which the SEC can pursue in parallel, allows a penalty of up to three times the profit gained or loss avoided through the illegal trade.⁸ The SEC can also seek an injunction barring the individual from serving as an officer or director of any public company, a consequence that can end a career without any prison time attached.

1
Office of the Law Revision Counsel. 15 USC 78j – Manipulative and Deceptive Devices
2
Justia Law. Chiarella v. United States, 445 U.S. 222
3
U.S. Securities and Exchange Commission. Assessing Materiality: Focusing on the Reasonable Investor When Evaluating Errors
4
eCFR. 17 CFR 240.10b5-1 – Trading on the Basis of Material Nonpublic Information in Insider Trading Cases
5
U.S. Securities and Exchange Commission. Rule 10b5-1 Insider Trading Arrangements and Related Disclosure
6
Supreme Court of the United States. United States v. O’Hagan, 521 U.S. 642
7
GovInfo. 15 USC 78ff – Penalties
8
Office of the Law Revision Counsel. 15 USC 78u-1 – Civil Penalties for Insider Trading