📜 What This Document Is 🗓️

This document is a Definitive Proxy Statement (DEF 14A), which is essentially a mandatory, detailed rulebook for the upcoming Annual Meeting of Stockholders. Think of it as a comprehensive guidebook that tells you exactly why the company needs to meet, who is running the show, and what votes you are being asked to cast.

Since the meeting is highly procedural and involves electing board members and approving auditors, the document doesn't contain financial performance numbers. Instead, it focuses entirely on governance, the people, and the rules. 👉 The main goal is to inform shareholders of key proposals and provide transparency regarding the company's leadership structure.

🧬 MBX Biosciences' Business Overview 🏥

MBX Biosciences, Inc. is a biopharmaceutical company focused on drug development. In simple terms, they are working in the complex, high-stakes world of science, aiming to create new treatments for diseases.

The company's principal executive offices are located at 11711 N. Meridian Street, Suite 300, Carmel, Indiana 46032. The board structure is based on three staggered classes of directors, a common practice that helps spread out director elections over multiple years.

🗓️ Annual Meeting Logistics 💻

The Annual Meeting of Stockholders is scheduled to take place online (virtual meeting) on June 4, 2026, at 8:00 AM Eastern Time.

Because this is a large, complex meeting, the company has set up multiple ways for shareholders to participate and vote:

• Attending Virtually: Shareholders must visit www.virtualshareholdermeeting.com/MBX2026 and use the control number provided in the notice to participate and vote electronically.
• Voting by Proxy (Absence): You can vote by Internet (www.proxyvote.com) up until 11:59 PM Eastern Time on Wednesday, June 3, 2026, or by calling 1-800-690-6903 until the same deadline.
• Key Date: The record date for determining who is entitled to vote is the close of business on April 10, 2026.

👉 Whether you plan to attend or not, the company emphasizes that your vote is crucial, and it is important to submit it early to ensure it is counted.

📜 Proposed Votes and Mandates 🗳️

The 2026 meeting has two primary items requiring shareholder votes, both proposed by the Board of Directors.

Electing Class II Directors

The board proposes electing Patrick J. Heron and Edward T. Mathers to serve as the Class II directors for a three-year term. This ensures that the company's leadership is constantly being refreshed.

Ratifying the Independent Auditor

The second proposal asks shareholders to ratify the appointment of Ernst & Young LLP to serve as the independent registered public accounting firm for the fiscal year ending December 31, 2026.

• Why it matters: Although shareholder approval is not legally required to appoint them, the board submits this vote because it is considered "good corporate governance," and failure to ratify could prompt the Audit Committee to reconsider retaining Ernst & Young.
• Audit Fees Trend: The fees paid to Ernst & Young for audit services show a significant reduction: the total fees were $491,678 in 2025, compared to $944,548 in 2024.

🔬 Scientific and Corporate Governance 🏆

MBX has structured its board with four specialized committees, designed to ensure that every major area of the company—from science to finance—is overseen by experts.

The Audit Committee 🔍

This committee (chaired by Laurie Stelzer) is responsible for the financial health of the company. Its duties include:

• Approving and pre-approving all services from the independent accounting firm (Ernst & Young LLP).
• Reviewing financial statements and the overall internal control structure.
• It confirmed that both the independent accounting firm and management will periodically meet privately with the Audit Committee.

The Compensation Committee 💰

(Chaired by Patrick Heron) This group focuses on executive pay. They review and recommend the compensation for the CEO and other officers, ensuring that compensation policies are competitive and fair.

The Nominating and Corporate Governance Committee 👥

(Chaired by Ora Pescovitz) This committee acts as the HR and selection arm of the board. They are responsible for:

• Identifying and evaluating all candidates for the board.
• Developing and recommending the overall corporate governance guidelines and code of ethics.

The Science and Medicine Committee 🧬

(Chaired by Steven Ryder) This is a specialized group dedicated to the core science of the company. They provide oversight for:

• The company’s research and development (R&D) pipeline.
• Nonclinical development, regulatory affairs, and clinical manufacturing activities.

👔 Director Leadership and Expertise 🧠

The board relies on deep experience across finance, biotech, and law. A significant portion of the directors are highly seasoned executives from the biopharma industry.

• P. Kent Hawryluk (CEO/Director): A co-founder who has extensive experience founding biopharma companies and has strong background in venture capital.
• Laurie Stelzer (Director): Brings decades of financial leadership experience, having served as CFO for multiple major biotech companies, including Mirati Therapeutics, Inc.
• Patrick J. Heron and Edward T. Mathers (Nominees): Both are highly experienced in the biopharma space, with backgrounds in venture capital, consulting, and service on numerous public company boards.
• Steven L. Hoerter (Director): Has deep experience leading commercial-stage biotechnology companies, having served as President and CEO of Deciphera Pharmaceuticals, Inc.
• Ora Pescovitz, M.D. (Director): Offers unmatched expertise combining academic, business, and medical experience, having served as an executive VP at the University of Michigan.

⚠️ Regulatory Compliance and Risk Oversight 📜

This section confirms the rules the company must follow, ensuring accountability and protecting the interests of shareholders.

• Emerging Growth Company Status: MBX is currently classified as an "emerging growth company." This status, permitted under the JOBS Act, allows the company temporary relief from certain public company reporting requirements. This status lasts until a specific date or key financial threshold is met (e.g., total annual gross revenue of $1.235 billion).
• Independence: The board determined that most directors are "independent," meaning they do not have personal or professional relationships with the company that would interfere with their ability to exercise impartial judgment.
• Risk Oversight: The board has overall oversight of risk management (which includes financial, operational, and strategic risks), and it has formally delegated this oversight responsibility to the Audit Committee.
• Clawback Policy: The Compensation Committee adopted a "clawback policy," meaning that if the company has to restate its financial statements due to material noncompliance, they must recover any incentive-based compensation given to past or present executives.

📞 Company Resources and Contacts 📍

For anyone needing more information, the filing provides specific resources and contact points.

• Websites: All logistical and voting information is available online at www.proxyvote.com, and the virtual meeting will be at www.virtualshareholdermeeting.com/MBX2026.
• Principal Executive Offices: For written communications or general inquiries, the company's mailing address is 11711 N. Meridian Street, Suite 300, Carmel, Indiana 46032.

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🧠 The Analogy — Proxy Battle 🗳️

Imagine the company board is running a club, and the annual meeting is the vote to decide who gets to sit on the committee next year. The Proxy Statement is the rulebook for the election. It doesn't show the club's monthly expenses (that's in the 10-K), but it shows you every single person running for a seat, what their background is, what specific rules govern the votes, and which votes need to be counted for the board to function next year.

🧩 Final Takeaway — Governance Matters 💡

This document is a massive corporate governance filing designed to provide transparency, not financial results. It signals that MBX is highly focused on structure, risk management, and expert oversight, which is critical for a biopharmaceutical company in its development stages.