Executive Assistant

Executive Assistant – Pioneering Business Unit (PBU)

Location: Cambridge, MA (On-site 4 days/week)

Flagship Pioneering’s Pioneering Business Units (PBUs) are where breakthrough science is transformed into high-impact ventures. Within this entrepreneurial environment, Jake Rubens — Origination Partner and PBU Lead — is seeking a highly motivated Executive Assistant (EA) to provide strategic and operational support.

This is a unique opportunity to work at the intersection of science, company building, and venture creation. The EA will play a central role in ensuring seamless operations for Jake and the PBU, anticipating needs, and driving execution across a dynamic portfolio.

The right candidate thrives in ambiguity, takes initiative, and acts as a trusted partner — equally comfortable managing complex multi-stakeholder projects as they are rolling up their sleeves for the small but essential details. This is a career-building role for a hustler who is eager to learn, thinks two steps ahead, and embraces every opportunity to make an impact.

What You’ll Do

• Executive Support & Calendar Management
• Own and manage Jake's executive calendar with precision, prioritizing competing demands across origination, PBU leadership, and external engagements
• Help track and manage incoming requests 
• Maintain a “decision tracker” – item’s pending Jake's decision, and outside decisions needed for the team to advance
• Support additional leadership in the PBU for large group meetings and essential travel
• Anticipate scheduling needs and proactively resolve conflicts.
• Operational & Strategic Coordination
• Coordinate meetings, key context, attendee bios, decision points, agendas, and follow-ups that advance Jake’s priorities and the PBU’s mission.
• Capture action items during meetings, then circulate with deadlines.
• Draft, edit, and manage internal and external communications on behalf of leadership, including help  assembling recurring reporting packets and updates.
• Partner with other EAs and Flagship central teams to ensure smooth collaboration.
• Project & Stakeholder Management
• Manage complex tasks involving multiple stakeholders across the PBU and Flagship ecosystem.
• Track incoming deliverables, close loops, and ensure execution against milestones.
• Support onboarding of new team members into the PBU
• Travel & Logistics
• Coordinate domestic and international travel, including detailed itineraries and expense reporting.
• Culture & Team Support
• Serve as a cultural ambassador for the PBU, organizing PBU events and team building activities in partnership with HR
• Be present and engaged in the office at least 4 days per week to support collaboration and onboarding.

Who You Are

• Experienced & Professional
• Bachelor’s degree required; 5+ years of experience supporting senior executives, preferably in fast-paced, high-growth environments.
• Demonstrated success supporting C-suite leaders or equivalent.
• Proactive & Entrepreneurial
• You don’t wait to be told — you anticipate, take initiative, and move projects forward.
• No task is too small if it advances the mission.
• Organized & Detail-Oriented
• Exceptionally strong at multitasking, prioritization, and maintaining accuracy under pressure.
• Skilled at managing sensitive information with discretion.
• Strong Communicator & Relationship Builder
• Excellent written and verbal communication skills; adept at representing leadership with polish.
• Effective at building trust and relationships across diverse stakeholders.
• Resilient & Resourceful
• Thrive in dynamic, ambiguous settings; flexible and solution-oriented.
• Energized by learning, growth, and tackling new challenges.
• Technically Proficient
• Advanced Outlook calendaring and scheduling skills; strong command of MS Office Suite (Word, PowerPoint, Excel).

Flagship Pioneering and our ecosystem companies are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity or Veteran status.

Recruitment & Staffing Agencies: Flagship Pioneering and its affiliated Flagship Lab companies (collectively, “FSP”) do not accept unsolicited resumes from any source other than candidates. The submission of unsolicited resumes by recruitment or staffing agencies to FSP or its employees is strictly prohibited unless contacted directly by Flagship Pioneering’s internal Talent Acquisition team. Any resume submitted by an agency in the absence of a signed agreement will automatically become the property of FSP, and FSP will not owe any referral or other fees with respect thereto.

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