Principal Engineer - Ledger Core

Team ResponsibilitiesYou will design and defend the single most important invariant that every quant model on this team ultimately depends on: that money is never created or destroyed as it moves through the system. The Ledger Core is the immutable, append-only, bi-temporal event store that every return, risk figure, and valuation traces back to. This role sets the boundary of the core itself, deciding with precision what belongs inside a small, provably correct kernel and what belongs outside it, and holds that line as the platform scales across asset classes and consuming teams.Key ResponsibilitiesWhat You'll OwnStorage design: the append-only prefix-KV layout underneath the event log, optimized for write-once, read-many access patterns and long-horizon replay.The money model: integer minor units, Int128 arithmetic, and versioned units, so that no rounding or float-drift error can ever enter the book of record a quant model would otherwise inherit.Conservation invariant: an exact-integer check enforced at the commit point, not reconciled after the fact.Commit protocol: vector-clock based commit ordering and consistent-cut semantics across concurrent writers.Core boundary discipline: the ongoing judgment call of what stays inside the immutable kernel versus what is pushed out to plug-in and quant services.Agentic Development ExpectationThis role sets the standard for how the rest of the team uses AI coding agents against the core. Because the ledger's correctness surface is small and its blast radius is large, you will define which parts of the core are safe to delegate to agentic implementation against a written invariant, and which parts require a human holding the pen. Expect to spend real time writing the specs and property tests that make agentic contribution to the core safe rather than expanding scope to accommodate it.Skills and Experience That Will Help You ExcelRequired Background8+ years building high-integrity, low-level storage or ledger systems in production, ideally in financial infrastructure, payments, or exchange-grade systems.Deep fluency in a modern, type-safe systems language (Go, Rust, or similar), with the ability to reason precisely about memory layout, allocation, and concurrency primitives.Hands-on experience with event sourcing and append-only log architectures at scale.Working command of MVCC, vector clocks, and consistent-cut / distributed-snapshot theory, not just familiarity with the terms.A demonstrated bias toward minimal, defensible cores over feature-accreting ones; you can point to a system where you said no to scope and were right to.Preferred / BonusPrior ownership of a ledger, general ledger engine, or exchange matching/settlement core.Experience with formal or semi-formal invariant specification (TLA+, Alloy, or comparable).Exposure to private markets or fund accounting data models.About MSCIWhat We Offer YouSalary range: $259,000 - $337,000 / year. Plus eligible for annual bonus.Transparent compensation schemes and comprehensive employee benefits, tailored to your location, ensuring your financial security, health, and overall wellbeing.Flexible working arrangements, advanced technology, and collaborative workspaces.A culture of high performance and innovation where we experiment with new ideas and take responsibility for achieving results.A global network of talented colleagues, who inspire, support, and share their expertise to innovate and deliver for our clients.Global orientation program to kickstart your journey, followed by access to our View email address on click.appcast.io platform, AI Learning Center, LinkedIn Learning Pro and tailored learning opportunities for ongoing skills development.Multi-directional career paths that offer professional growth and development through new challenges, internal mobility and expanded roles.We actively nurture an environment that builds a sense of inclusion belonging and connection, including eight Employee Resource Groups. All Abilities, Asian Support Network, Black Leadership Network, Climate Action Network, Hola! MSCI, Pride & Allies, Women in Tech, and Women's Leadership Forum.At MSCI we are passionate about what we do, and we are inspired by our vision – to power better decisions. You'll be part of an industry-leading network of creative, curious, and entrepreneurial pioneers. This is a space where you can challenge yourself, set new standards and perform beyond expectations for yourself, our clients, and our industry.MSCI strengthens global markets by connecting participants across the financial ecosystem with a common language. Our research-based data, analytics and indexes, supported by advanced technology, set standards for global investors and help our clients understand risks and opportunities so they can make better decisions and unlock innovation. We serve asset managers and owners, private-market sponsors and investors, hedge funds, wealth managers, banks, insurers and corporates.MSCI Inc. is an equal opportunity employer. It is the policy of the firm to ensure equal employment opportunity without discrimination or harassment on the basis of race, color, religion, creed, age, sex, gender, gender identity, sexual orientation, national origin, citizenship, disability, marital and civil partnership/union status, pregnancy (including unlawful discrimination on the basis of a legally protected parental leave), veteran status, or any other characteristic protected by law. MSCI is also committed to working with and providing reasonable accommodations to individuals with disabilities. If you are an individual with a disability and would like to request a reasonable accommodation for any part of the application process, please email View email address on click.appcast.io and indicate the specifics of the assistance needed.To All Recruitment AgenciesMSCI does not accept unsolicited CVs/Resumes. Please do not forward CVs/Resumes to any MSCI employee, location, or website. MSCI is not responsible for any fees related to unsolicited CVs/Resumes.Note on Recruitment ScamsWe are aware of recruitment scams where fraudsters impersonating MSCI personnel may try and elicit personal information from job seekers. Read our full note on careers.msci.com