Insider Dealing and the Classical Theory

In 1975, a printer named Vincent Chiarella worked at a financial printing firm handling confidential tender offer documents for corporate clients. He worked out which companies were takeover targets from the documents themselves, before the deals were announced, and traded on it. The Supreme Court eventually overturned his conviction. Not because he lacked material non-public information — he plainly had it — but because he owed no duty of trust to the companies whose stock he traded. That single case defines what's called the classical theory of insider trading, and it's the reason US insider trading law is narrower than most people assume.

The rule is about duty, not secrets

US insider trading liability under the classical theory requires two things together, not one:

1. Material non-public information — a genuine informational advantage (see What Makes Information Material and Non-Public).
2. A breach of a fiduciary duty — owed specifically to the shareholders of the company whose stock is traded, most obviously by that company's own officers, directors and employees.

Person	Has MNPI?	Owes a duty to the company's shareholders?	Classical theory liability
Company CFO who trades on unreleased earnings	Yes	Yes	Liable
Company employee who tips a friend, who trades	Yes (via tip)	Yes, the employee does; the friend inherits it if they knew the tip breached a duty	Both can be liable
Outside printer with no relationship to the company (Chiarella)	Yes	No	Not liable under the classical theory

The insight is genuinely counterintuitive: it is not automatically illegal, under the classical theory alone, to trade on a real informational advantage that fell into your hands with no duty attached. What makes it illegal is trading in breach of a trust relationship with the people on the other side of the trade.

Why regulators didn't stop at the classical theory

The Chiarella outcome left an obvious gap: someone with no direct duty to a company's shareholders could still trade on stolen or misappropriated confidential information and, under the classical theory alone, escape liability. Courts and regulators closed most of that gap with a second, broader legal theory — the misappropriation theory, which instead asks whether the trader breached a duty to the source of the information, even if that source isn't the company being traded. A lawyer at a firm advising on a merger who trades ahead of the announcement breaches a duty to their own firm and client, not to the target company's shareholders directly — and is liable under misappropriation even where the classical theory alone wouldn't reach them. That extension is covered in The Misappropriation Theory of Insider Trading.

Tipper-tippee liability

The Dirks case in 1983 extended the classical theory to people who never worked for the company at all: someone who receives a tip is liable if they knew or should have known the tip breached the tipper's duty, and — critically — the tipper personally benefited from giving it, whether financially or even just reputationally (helping a friend counts). A tippee who genuinely had no idea the information came from a breach of duty has a real defense; one who should obviously have known does not.