Mersana Therapeutics, Inc.

Mersana Therapeutics, Inc. insiders are currently net buyers of MRSN stock, showing bullish sentiment over the past 90 days. Executives have purchased $226.8M while selling $4.8M, resulting in a positive net flow of $222.1M. This buying activity represents 98% of total transaction volume.

Mersana Therapeutics, Inc. has 31 active insiders who have filed SEC Form 4 transactions in the past 90 days. Andrew A. F. Hack (Executive) leads with 20 transactions totaling $43.8M. David M. Mott (Executive) follows with 20 transactions worth $33.0M. Open-market purchases require insiders to invest their own capital, demonstrating genuine conviction.

The Insider Alignment Score measures the ratio of buying to selling activity on a 0-100 scale. Mersana Therapeutics, Inc.'s current score of 98/100 indicates bullish insider sentiment. Scores above 60 suggest insiders are accumulating shares faster than selling, reflecting $226.8M in purchases versus $4.8M in sales.

The most recent insider transaction occurred on Oct 27, 2025, when Bala Mohan (Executive) disposed of 77 shares at $9.90 per share for $762. This appears to be a discretionary trade.

Based on SEC Form 4 filings from the past 90 days, MRSN insider trading sentiment is currently bullish with an Alignment Score of 98/100. The net insider flow of $222.1M reflects accumulation, with 98% of volume being purchases.

SEC Form 4 is the primary disclosure mechanism for insider trading at publicly traded companies like Mersana Therapeutics, Inc.. Corporate insiders must file within two business days of any transaction, making it one of the most timely sources of executive sentiment. At MRSN, we track all Form 4 filings—currently showing 430 transactions from 31 insiders over 90 days.

A 10b5-1 plan allows Mersana Therapeutics, Inc. executives to pre-schedule stock sales when they don't possess material non-public information. At MRSN, approximately 66% of recent transactions are 10b5-1 trades. This high percentage suggests much of the selling is routine and pre-planned.

You can monitor Mersana Therapeutics, Inc. (MRSN) insider trading activity on this page, which updates within hours of new SEC Form 4 filings. We track all 31 active insiders and provide real-time transaction feeds, the Alignment Score, 10b5-1 vs. discretionary breakdowns, and direct links to SEC EDGAR filings.

Our Alignment Score measures the ratio of insider buying to selling on a scale of 0-100. A score above 70 indicates strong bullish sentiment, while below 30 suggests bearish activity. Mersana Therapeutics, Inc.'s current score of 98/100 indicates strong bullish sentiment with executives accumulating shares. This is calculated from $226.8M in purchases versus $4.8M in sales over 90 days, resulting in a net flow of $222.1M.

SEC Form 4 filings are mandatory reports that Mersana Therapeutics, Inc. insiders must submit within 2 business days. Each filing includes the insider's name, relationship, transaction type, shares, and price. Transaction codes: P (purchase), S (sale), A (award), M (option exercise), G (gift). At MRSN, the most common type is "A" with 23 occurrences. The most recent Form 4 was filed on Oct 27, 2025 by Bala Mohan.

Rule 10b5-1 allows corporate insiders to establish pre-scheduled trading plans when they don't possess material non-public information. At Mersana Therapeutics, Inc., approximately 66% of recent transactions are executed under 10b5-1 plans, while 34% appear to be discretionary trades. This high percentage suggests selling activity may be routine diversification.