Execution Platform Re-Architecture
for a Top-10 Broker-Dealer
How we replaced a decade-old Java trading system with a sub-millisecond Rust/C++ execution engine — processing $2B+ daily with five-nines availability and passing SOC 2 and PCI DSS on the first audit attempt.
A top-10 independent broker-dealer facing a latency ceiling
Our client is one of the ten largest independent broker-dealers in the US by assets under management, with institutional trading desks across equities, options, and fixed income. They had been running their execution infrastructure on a Java-based platform built a decade earlier — a system that had served them well when daily volumes were under $500M and strategy latency requirements were measured in milliseconds.
As volumes doubled past $1B and their quantitative strategies became increasingly latency-sensitive, the platform's fundamental architecture became the constraint. The firm had reached the ceiling of what Java could deliver, and they knew it. The question was how to re-platform without disrupting $1B+ in daily active trading.
Where microseconds mean millions
The Java platform was introducing GC pause jitter in the 5–15ms range — unpredictable latency spikes that caused strategy underperformance during high-volatility events. The quantitative research team had identified multiple high-frequency strategies that were economically viable at sub-millisecond latency but unviable at the platform's actual p99 latency of 8ms.
Beyond latency, the monolithic architecture required full system restarts for any code deployment. Every strategy update meant a maintenance window. Risk management ran on a separate system with a 30-second reconciliation delay — a 30-second blind spot in the risk picture during volatile markets that the firm's compliance team had flagged as a material concern.
The firm was also facing an impending PCI DSS audit that their existing infrastructure could not pass. The combination of latency problems, operational rigidity, risk management gaps, and compliance exposure made a full re-platform unavoidable. The constraint was doing it without market disruption.
What we learned the hard way
DPDK kernel-bypass validation revealed infrastructure gaps
We had scoped DPDK kernel-bypass networking as a straightforward configuration task. In practice, the firm's co-location provider had a specific NIC firmware version that required a custom DPDK driver patch. This took three weeks to resolve and required sourcing a hardware specialist with direct NIC vendor access. The lesson: validate your kernel-bypass assumptions in the actual production environment, not in dev.
Parallel run strategy exposed position reconciliation edge cases
Our parallel-run validation approach — running both systems simultaneously on identical order flow — surfaced 14 edge cases in fill price reconciliation that existed in the legacy system and had never been caught. Each had to be analyzed, a canonical correct behavior defined, and the new system validated against it. This added four weeks to the validation phase but prevented what would have been regulatory reporting discrepancies.
PCI DSS audit scope was larger than anticipated
We had scoped PCI DSS compliance as primarily a data-at-rest encryption problem. The auditors required cardholder data environment segmentation that extended into the market data feed infrastructure, which we hadn't anticipated. This required a network re-segmentation effort that added six weeks and a secondary architecture review. Compliance scope always expands — plan the contingency in.
Deterministic performance, by design
The execution core was built in Rust for its zero-cost abstractions, guaranteed memory safety without garbage collection, and predictable performance characteristics. The critical hot path — from market data ingestion through strategy evaluation to order submission — was designed as a single-threaded, lock-free pipeline running on isolated CPU cores with DPDK kernel-bypass networking. GC jitter: zero.
The matching engine and specific risk check components were written in C++, where nanosecond-level optimization required custom memory allocators with pre-allocated object pools. Strategy modules were implemented as dynamically linked libraries, enabling hot-deployment during market hours without restarting the execution core — eliminating maintenance windows entirely.
The real-time risk management system was integrated directly into the order flow pipeline rather than running as a separate reconciliation process. Every order passes through position limits, exposure checks, and market impact analysis inline, with results replicated synchronously across data centers. The 30-second reconciliation lag was eliminated.
The parallel-run migration strategy was key to the risk-free cutover. Both the legacy Java platform and the new Rust platform processed identical live order flow simultaneously for 20 weeks, with automated reconciliation validating execution quality, fill rates, and latency distributions across every trading session. The legacy system was decommissioned only after both systems agreed on every metric for 60 consecutive trading days.
Engineered for zero compromise
Lock-Free Execution Core
Single-threaded Rust pipeline on isolated CPU cores with DPDK kernel-bypass networking. Deterministic sub-millisecond latency with zero GC pauses.
Inline Risk Engine
Pre-trade risk checks integrated directly into the order flow. Position limits, exposure analysis, and market impact evaluated in under 100 microseconds — not 30 seconds.
Active-Active Deployment
Synchronous state replication across geographically separated data centers. Deterministic failover preserving position accuracy to the microsecond with zero data loss.
Real-Time Analytics Dashboard
WebSocket-powered React dashboard with sub-second market data visualization, P&L tracking, and strategy performance monitoring for institutional traders.
Performance that opened new markets
$2B+ Daily Volume
Processing over $2 billion in daily transaction volume across equities, options, and fixed income with full audit trail and regulatory reporting to the microsecond.
<1ms Execution Latency
Sub-millisecond order-to-execution latency achieved through kernel-bypass networking, lock-free data structures, and co-located infrastructure.
99.999% Availability
Five-nines availability through active-active deployment, deterministic failover, and real-time state replication across geographically separated data centers.
SOC 2 + PCI DSS
Both certifications achieved on first audit attempt. Hardware security modules for key management, encrypted pipelines, and real-time anomaly detection.
Post-launch, the firm doubled their daily volume capacity to $2B+ and onboarded three new institutional clients whose latency requirements the legacy platform could not meet. The deterministic performance characteristics eliminated the tail-latency spikes that had previously caused strategy underperformance during high-volatility market events.
Both SOC 2 Type II and PCI DSS certifications were achieved on the first audit attempt. The parallel-run migration strategy resulted in zero trading disruptions during the 20-week cutover period — a fact the firm's COO cited as the defining success criterion for the engagement.
Key Technical Decisions
- Chose Rust over C++ for the execution core — memory safety guarantees reduced bug density in a zero-tolerance environment
- Inline risk management over reconciliation — eliminated a 30-second compliance blind spot that had existed for years
- 20-week parallel run before decommission — added cost but eliminated migration risk in a regulated, zero-disruption-tolerance environment
- Hot-deployable strategy modules via dynamic linking — eliminated all maintenance windows for strategy deployments
The stack
Reference Available Upon Request
This client is referenceable. We can arrange a direct conversation with their CTO or Head of Electronic Trading for qualified enterprise prospects under mutual NDA. SOC 2 and PCI DSS documentation available separately.
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