Principal Engineer - Ledger Core

MSCI Inc.•New York, NY

7d•$259,000 - $337,000•Hybrid

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 resides outside, and maintain these boundaries as the platform scales. A significant aspect of the role involves setting the standard for how AI coding agents are used for development within the core, defining safe delegation practices based on written invariants and property tests, rather than expanding the scope to accommodate AI.

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.
Demonstrated bias toward minimal, defensible cores over feature-accreting ones; ability to say no to scope and be correct about it.

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.
Define the boundaries of the Ledger Core, determining what belongs within the kernel and what resides outside.
Design the append-only prefix-KV layout for the event log, optimized for write-once, read-many access and long-horizon replay.
Develop and maintain the money model using integer minor units, Int128 arithmetic, and versioned units to prevent rounding or float-drift errors.
Implement and enforce an exact-integer conservation invariant at the commit point.
Develop the commit protocol using vector-clock based ordering and consistent-cut semantics for concurrent writers.
Exercise judgment on 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 writing necessary specs 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.
Access to Learning@MSCI platform.
Access to AI Learning Center.
Access to LinkedIn Learning Pro.
Tailored learning opportunities for ongoing skills development.
Multi-directional career paths offering professional growth and development.
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).