Principal Engineer - Ledger Core

MSCI•New York, NY

About The Position

This role is for a Principal Engineer on the Ledger Core team. The primary responsibility is to design and defend the core invariant that ensures money is never created or destroyed within the system. The Ledger Core is an immutable, append-only, bi-temporal event store that serves as the foundation for all financial calculations. The engineer will define the boundaries of this core, determining what belongs within the kernel and what is external, and maintain these boundaries as the platform scales. Additionally, this role involves setting the standard for how AI coding agents are used for development within the core, defining safe delegation practices and focusing on written invariants and property tests for agentic contributions.

Requirements

8+ 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.
A demonstrated bias toward minimal, defensible cores over feature-accreting ones; ability to say no to scope and be correct.

Nice To Haves

Prior 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.

Responsibilities

Design and defend the core invariant that ensures money is never created or destroyed as it moves through the system.
Define the boundaries of the Ledger Core, determining what belongs inside the kernel and what is external.
Maintain the core boundaries as the platform scales across asset classes and consuming teams.
Own the storage design, including the append-only prefix-KV layout optimized for write-once, read-many access and long-horizon replay.
Own the money model, including integer minor units, Int128 arithmetic, and versioned units to prevent rounding or float-drift errors.
Implement and enforce the conservation invariant as an exact-integer check at the commit point.
Develop the commit protocol, including vector-clock based commit ordering and consistent-cut semantics for concurrent writers.
Define the core boundary discipline, making ongoing judgment calls about what stays within the immutable kernel versus what is pushed out to plug-in and quant services.
Set the standard for AI coding agent usage against the core, defining safe delegation practices and focusing on written invariants and property tests.

Benefits

Salary range: $259,000 - $337,000 / year.
Eligible for annual bonus.
Transparent compensation schemes.
Comprehensive employee benefits, tailored to your location.
Flexible working arrangements.
Advanced technology.
Collaborative workspaces.
Culture of high performance and innovation.
Global network of talented colleagues.
Global Orientation program.
Access to Learning@MSCI platform, AI Learning Center, LinkedIn Learning Pro, and tailored learning opportunities.
Multi-directional career paths for professional growth and development.
Environment that builds a sense of inclusion, belonging, and connection.
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).