Madrigal Pharma: Mills Brothers Buy $150 Million in Stock — A Rare Insider Conviction Signal

While most insider transaction headlines cover selling, Madrigal Pharmaceuticals (MDLN) has produced one of the most remarkable insider buying signals in recent biotech history. Brothers Charles N. Mills and Andrew J. Mills have purchased a combined $149.8 million in Madrigal stock with their own money.

$75 Million Each: The Mills Brothers' Bet

Andrew J. Mills has bought $75.0 million in Madrigal shares across 3 transactions. His brother Charles N. Mills has purchased $74.8 million across 4 transactions. The near-identical amounts suggest a coordinated investment thesis between the siblings.

To put this in perspective: most insider buys range from $50,000 to $5 million. A $150 million open-market purchase by insiders is exceptionally rare — placing this among the top insider buying events across all public companies, not just biotech.

The Numbers

Insider	Total Purchased	Transactions	Total Sold
Andrew J. Mills	$75.0M	3	$0
Charles N. Mills	$74.8M	4	$0

Notably, neither brother has sold a single share. The $149.8 million represents pure conviction buying with zero offsetting sales — a clean, unambiguous bullish signal.

Why This Matters

Academic research consistently shows that insider buying is a far more reliable signal than insider selling. Executives sell for many reasons (diversification, taxes, lifestyle) but buy for only one: they believe the stock is going up. When insiders commit $150 million of personal capital, the conviction level is extraordinary.

What Is Madrigal?

Madrigal Pharmaceuticals is a biotech focused on metabolic dysfunction-associated steatohepatitis (MASH), formerly known as NASH. The company's drug Rezdiffra (resmetirom) became the first FDA-approved treatment for MASH in March 2024 — a landmark approval for a disease affecting an estimated 6-8 million Americans.

The MASH market is projected to exceed $10 billion annually, and Rezdiffra currently has first-mover advantage with no approved competitors. The Mills brothers' $150 million bet appears to reflect their view that the market has not yet fully priced in the commercial opportunity.

The Contrarian Signal

In a market where insider selling dominates the headlines — CEOs routinely cashing out hundreds of millions — the Madrigal buying stands in stark contrast. While biotech stocks face broad skepticism, two insiders have put $150 million on the line that this particular company is undervalued.

Follow Madrigal Pharmaceuticals insider activity on the MDLN stock page.