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Big Internet Seller Services Inc; New York (NY); On-site; USD 200,000 - 260,000; Full time

Job summary

Flex is building the AI-native private bank for business owners, with roles available in Miami or NYC and travel required. You will join the founding team of the Office of the CEO to tackle the company’s highest-priority problems, often without a playbook, and directly impact strategic decisions.

The role demands 3–5 years in top-tier finance or consulting, extreme rigor, and the ability to thrive in ambiguity while delivering fast results. Expect intense weeks and meaningful impact from day one.

Qualifications

• 3–5 years in top-tier investment banking (TMT/fintech coverage), private equity, management consulting, late-stage venture capital, or a fast-growing startup.
• A track record of outperformance — clear signals you were trusted with more scope, faster, than your peers.
• Strong quantitative and analytical skills: advanced Excel, working knowledge of SQL, and comfort dissecting messy data and building models from scratch.
• Extreme rigor and comfort operating in ambiguity at speed — priorities here change faster than the plan does.
• Demonstrated ability to sustain a high-intensity pace: this role will regularly require ~12-hour days, 5–6 days a week, especially in year one.
• This role is based in Miami or NYC but will involve travel.

Responsibilities

• Take on the CEO’s highest-priority problems directly — strategic projects, market research and competitive work, financial analysis, and cross-functional execution, often with no existing playbook.
• Identify problems, develop solutions, and execute them; often working on multiple initiatives.
• Build and own the models and analyses that inform major company decisions.
• Collaborate with and move fluidly across various departments as business priorities shift.
• As the early stages of this team grows, you will help recruit, ramp, and manage the associates who join after you.

Skills

Advanced Excel

SQL

Financial modeling

Data analysis

Job description

Flex is building the AI-native private bank for business owners.

We’re re-architecting the entire financial system for entrepreneurs—from the first dollar a business earns to how that value compounds, moves, and is ultimately spent in real life. Banking, credit, payments, personal finance, and financial operations—rebuilt from the ground up as a single, intelligent system. Flex is the full financial home for ambitious owners.

Since launching publicly in September 2023, Flex has scaled from zero to nine-figure annualized revenue, with a clear path to profitability by late 2026. We move fast, ship relentlessly, and operate with extreme ownership.

Our customers are affluent business owners ($3–$200M in revenue)—the backbone of the economy and one of the most underserved segments in finance. They’re stuck with outdated banks and fragmented tools. We’re replacing all of it. The opportunity is massive: a ~$1T+ revenue market hiding in plain sight. Our ambition is to build a $100B+ company by delivering a product that is fundamentally better—not incrementally improved.

Flex has raised $100M+ in equity and $300M+ in debt.

- Mission-critical problems: We build software that directly controls how money moves at scale.

- High bar, low ego: Small teams, exceptional people, real ownership.

- Speed over comfort: We prioritize execution, quality, clarity, and results.

- Enduring impact: What we’re building will define how a generation of owners runs their businesses.

Team & Locations

We hire exceptional people who want to build hard things and see their work matter immediately. Roles are available in: San Francisco, Miami, New York, and fully remote.

Flex Fuels Ambition.

About the Role

This is a new program and the chance to be part of the founding team of the Office of the CEO. We’re creating a small team of high-caliber operators working directly for our Founder & CEO on whatever the company’s highest-priorities are. It is not a rotational program or a fixed analyst lane — scope is set by what the company needs solved, not by a job description. You will be the one to help identify what these opportunities are.

What You'll Do

Take on the CEO’s highest-priority problems directly — strategic projects, market research and competitive work, financial analysis, and cross-functional execution, often with no existing playbook

Identify problems, develop solutions, and execute them; often working on multiple initiatives

Build and own the models and analyses that inform major company decisions

Collaborate with and move fluidly across various departments as business priorities shift

As the early stages of this team grows, you will help recruit, ramp, and manage the associates who join after you

Requirements

3–5 years in top-tier investment banking (TMT/fintech coverage), private equity, management consulting, late-stage venture capital, or a fast-growing startup

A track record of outperformance — clear signals you were trusted with more scope, faster, than your peers

Strong quantitative and analytical skills: advanced Excel, working knowledge of SQL, and comfort dissecting messy data and building models from scratch

Extreme rigor and comfort operating in ambiguity at speed — priorities here change faster than the plan does

Demonstrated ability to sustain a high-intensity pace: this role will regularly require ~12-hour days, 5–6 days a week, especially in year one

This role is based in Miami or NYC but will involve travel

Nice to Haves

Ideal background in math, physics, or another highly quantitative field

Understanding of fintech, banking, or financial infrastructure

Compensation

The starting base salary for this role is $200k+ equity. This is a full-time role with benefits. Final compensation is commensurate with candidate experience, work location, and interview performance.

Additional Information

Why Join Us

Build something generational — Capture the full lifecycle of money for ambitious business owners.

Work on real money, real risk — Payments, credit, and banking at serious scale.

Solve hard problems — AI, underwriting, compliance, and global finance from first principles.

True ownership — Small teams, high trust, real accountability.

Founder-level exposure — Direct access to leadership, customers, and investors.

High bar, high taste — Move fast without cutting corners.

Elite peers — People here are builders, not tourists.

Real upside — Meaningful equity if you help build something big.