Shadow Trading and the SEC’s Panuwat Case Explained

Most coverage of shadow trading insider trading is written for corporate compliance attorneys. The mechanics are buried under legal citations, and the retail investor angle (why this matters when reading Form 4 filings or watching unusual sector options activity) gets lost entirely.

This post translates the Panuwat case into plain English: what happened, why the SEC won, what the 9th Circuit appeal means, and why the expanding boundary of insider trading law should change how you interpret pre-announcement activity in sector peer stocks.

What Shadow Trading Actually Is

Classical insider trading is straightforward: an executive learns something material and nonpublic about their own company (an upcoming earnings miss, a drug trial failure, a pending acquisition) and trades that company’s stock before the news is public. The duty runs from the insider to their company’s shareholders. That relationship is clear.

Shadow trading is the same logic applied one company over. The insider still possesses material nonpublic information (MNPI) about their own employer. But instead of trading their employer’s stock, they trade in a peer, competitor, or otherwise economically linked companywhose stock price will predictably move when the source company’s news goes public.

The intuition is simple: if you know Medivation is about to be acquired by Pfizer at a big premium, and Incyte is a similarly sized oncology-sector company that the market will immediately re-rate as an acquisition candidate—buying Incyte options is economically equivalent to front-running the deal. You just did it one ticker away from where regulators were trained to look.

The Panuwat Case: A Seven-Minute Trade That Changed Insider-Trading Law

Matthew Panuwat was Senior Director of Business Development at Medivation Inc., an oncology-focused biopharmaceutical company based in San Francisco. Part of his job was to monitor pharmaceutical industry M&A and track Medivation’s peer companies and their stock prices. He knew the sector cold.

On August 18, 2016, Medivation’s CEO emailed Panuwat that Pfizer’s acquisition of Medivation was imminent. Within seven minutes of receiving that email, Panuwat purchased short-term, out-of-the-money call options on Incyte Corporation—a direct Medivation competitor in the same oncology segment. He had never previously traded Incyte stock or options.

Four days later, on August 22, 2016, Pfizer publicly announced the Medivation acquisition. Incyte’s stock rose 7.7% on the news—exactly the kind of sector re-rating Panuwat had anticipated. He sold his Incyte options for approximately $240,000, realizing illicit profits of roughly $107,066.

The SEC filed its civil complaint against Panuwat in August 2021. After nearly three years of pretrial litigation, the case went to a jury. On April 5, 2024, after an eight-day trial and a few hours of deliberation, the jury returned a verdict in favor of the SEC—the first successful enforcement action based on the shadow-trading theory in U.S. history.

How the Misappropriation Theory Reaches a Different Company’s Stock

The SEC didn’t invent a new law to prosecute Panuwat. It used the existing misappropriation theory—the same framework established in United States v. O’Hagan (1997) that applies when an outsider misuses confidential information obtained in violation of a duty to the source. The twist in Panuwat was making two moves that the SEC had not previously tested together.

Step one: materiality.The MNPI about Medivation’s acquisition was material not just to Medivation shareholders, but to Incyte investors. Both were mid-cap oncology companies. When Pfizer paid a large premium for Medivation, the market would logically conclude that similarly situated peers were also undervalued as acquisition targets. The acquisition news was therefore material to Incyte’s stock price even though Incyte was not the target.

Step two: duty. The key weapon the SEC used was Medivation’s own insider-trading policy. That policy didn’t just prohibit employees from trading Medivation securities while in possession of MNPI. It prohibited using MNPI to trade any publicly traded company’ssecurities. By trading Incyte, Panuwat breached a duty he owed to Medivation under the company’s own written policy. The employer’s policy became the sword, not just a shield.

This is the structural insight that makes shadow trading legally coherent: the insider doesn’t need to trade the target company’s stock. If the information they possess is material to a peer company’s stock, and their employer’s policy forbids trading on that information in any security, then trading the peer breaches the duty. The misappropriation theory travels wherever the MNPI travels.

Case Two: Bechtolsheim and the Acacia Settlement

Panuwat was not a one-off experiment. In March 2024, weeks before the Panuwat jury verdict, the SEC filed a second shadow-trading action against Andreas Bechtolsheim, the billionaire co-founder of Sun Microsystems and former chairman and CEO of Arista Networks.

The facts follow the same structure as Panuwat, applied to the technology sector. Bechtolsheim allegedly learned through Arista’s relationship with a third-party company that Acacia Communicationswas about to be acquired by Cisco. On July 8, 2019, he purchased Acacia put options through brokerage accounts held in the name of a relative and an associate, an apparent attempt to conceal the trading. Cisco announced the acquisition the next day. Acacia’s stock jumped 35.1%. Bechtolsheim’s profits totaled $415,726.

He settled. On May 30, 2024, a federal judge in the Northern District of California approved a final judgment against Bechtolsheim for a civil penalty of $923,740 (more than double his profits) and a five-year bar from serving as an officer or director of a public company. He did not admit or deny the allegations.

Two shadow-trading enforcement actions in a single year, across two different sectors, against two high-profile defendants. The SEC framed shadow trading as a form of insider trading that harms market integrity by letting insiders circumvent their own company’s restrictions while still exploiting confidential information. That framing makes clear the agency intends to keep using this theory.

What Academic Research Says About How Widespread This Actually Is

The Panuwat case gave the SEC’s enforcement theory a name, but the phenomenon predates the lawsuit. In 2021, Mihir N. Mehta (University of Michigan), David M. Reeb (NUS Business School), and Wanli Zhao published “Shadow Trading” in The Accounting Review (Vol. 96, No. 4)—the founding empirical study of the concept.

Their findings are striking. Measuring abnormal short interest, abnormal options volume, and price run-up in peer companies before major source-firm announcements, they found that target firms experience a 12% to 17% increase in symptoms of informed tradingin the window before the source firm releases private information. The paper concludes that shadow trading is “an undocumented and widespread mechanism that insiders use to avoid regulatory scrutiny.”

Two findings stand out. The shadow-trading effect is significantly stronger when source firms have no explicit policyrestricting shadow trading by employees, which is exactly the policy gap the Panuwat case exposed. And the effect is concentrated in the window before major earnings announcements and M&A disclosures, with biotech and pharma showing some of the strongest signals.

The 9th Circuit Appeal: What Is at Stake

Panuwat appealed the April 2024 jury verdict to the U.S. Court of Appeals for the Ninth Circuit (case No. 24-6882), where oral argument is expected in June or July 2026 in San Francisco.

The central question before the court is whether insider trading liability can extend beyond the company to which the MNPI directly relates to a different, economically linked company. If the Ninth Circuit affirms, shadow trading shifts from experimental enforcement to a regularized, repeatable SEC tool. Every public-company employee with access to material nonpublic information will need to know that their trading window extends beyond their own employer’s ticker.

If the court reverses, the SEC’s shadow-trading theory gets set back significantly until Congress acts or a different circuit creates a split.

The opposition is organized. The U.S. Chamber of Commerce filed an amicus brief arguing the theory lacks a statutory basis and creates unpredictable liability for corporate employees. The Chamber argues that expanding insider trading to cover companies beyond the one where the insider works would chill legitimate investment activity. AIMA (the global hedge fund trade body) also filed an amicus brief arguing the SEC has not defined “economically linked company” clearly enough for market participants to know when they are legally exposed.

How Companies Are Already Responding

The compliance infrastructure around shadow trading is hardening fast. Companies are not waiting for the 9th Circuit to decide.

Microsoft updated its insider-trading policy, filed as Exhibit 19 to its Form 10-K on EDGAR, to explicitly prohibit trading in securities of “an economically linked company such as a competitor of Microsoft” when an employee possesses MNPI obtained through their Microsoft role. That language directly mirrors the SEC’s framing from the Panuwat case, making Microsoft one of the first major public companies to publicly codify the concept in a mandatory SEC filing.

The timing is not coincidental. Beginning with fiscal-year 2024 filings submitted in 2025, the SEC now requires all public companies to include their insider-trading policy as an exhibit to the Annual Report on Form 10-K. That means shadow-trading language, or its conspicuous absence, is now publicly searchable on EDGAR for every listed company. Law firms are advising clients to audit whether their policies cover trading in securities of customers, suppliers, competitors, and other economically linked entities.

What This Means When You Read Form 4 Filings

Here is the payoff for MarketPeel’s audience. If you read Form 4 filings to follow insider activity, shadow trading adds a layer of interpretation that most retail investors haven’t considered.

The Mehta, Reeb & Zhao study found that informed-trading symptoms in peer companies are concentrated in the window immediately before major earnings announcements and M&A disclosures, precisely the scenarios where sector insiders are most likely to possess MNPI. If you see unusual option activity in a pharma or biotech company that has no obvious near-term catalyst of its own, one possible explanation is that an insider at a sector peer has information that makes this company an attractive trade.

This doesn’t mean you should chase every unexplained options spike in a sector. It means you should understand whysuch signals exist, what the legal landscape around them looks like, and how the SEC is now actively policing this space. Understanding the legal framework is not investment advice. It’s context that makes the data more readable.

The broader point is that shadow trading shows how insider-trading law continues to expand beyond the boundaries most people assume. The Form 4 system and the 10b5-1 safe harbor framework were designed around an insider trading their own company’s stock. Shadow trading operates in the space those rules don’t cover. The SEC is now actively filling that gap through enforcement.