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Tuesday, September 9, 2025

Morgan Stanley’s DevGen.AI: Reshaping Enterprise Legacy System Modernization Through Generative AI

September 09, 2025

As enterprises increasingly grapple with the pressing challenge of modernizing legacy software systems, Morgan Stanley has unveiled DevGen.AI—an internally developed generative AI tool that sets a new benchmark for enterprise-grade modernization strategies. Built upon OpenAI’s GPT models, DevGen.AI is designed to tackle the long-standing issue of outdated systems—particularly those written in languages like COBOL—that are difficult to maintain, adapt, or scale within financial institutions.

The Innovation: A Semantic Intermediate Layer

DevGen.AI’s most distinctive innovation lies in its use of an “intermediate language” approach. Rather than directly converting legacy code into modern programming languages, it first translates source code into structured, human-readable English specifications. Developers can then use these specs to rewrite the system in modern languages. This human-in-the-loop paradigm—AI-assisted specification generation followed by manual code reconstruction—offers superior adaptability and contextual accuracy for the modernization of complex, deeply embedded enterprise systems.

By 2025, DevGen.AI has analyzed over 9 million lines of legacy code, saving developers more than 280,000 working hours. This not only reduces reliance on scarce COBOL expertise but also provides a structured pathway for large-scale software asset refactoring across the firm.

Application Scenarios and Business Value at Morgan Stanley

DevGen.AI has been deployed across three core domains:

1. Code Modernization & Migration

DevGen.AI accelerates the transformation of decades-old mainframe systems by translating legacy code into standardized technical documentation. This enables faster and more accurate refactoring into modern languages such as Java or Python, significantly shortening technology upgrade cycles.

2. Compliance & Audit Support

Operating in a heavily regulated environment, financial institutions must maintain rigorous transparency. DevGen.AI facilitates code traceability by extracting and describing code fragments tied to specific business logic, helping streamline both internal audits and external regulatory responses.

3. Assisted Code Generation

While its generated modern code is not yet fully optimized for production-scale complexity, DevGen.AI can autonomously convert small to mid-sized modules. This provides substantial savings on initial development efforts and lowers the barrier to entry for modernization.

A key reason for Morgan Stanley’s choice to build a proprietary AI tool is the ability to fine-tune models based on domain-specific semantics and proprietary codebases. This avoids the semantic drift and context misalignment often seen with general-purpose LLMs in enterprise environments.

Strategic Insights from an AI Engineering Milestone

DevGen.AI exemplifies a systemic response to technical debt in the AI era, offering a replicable roadmap for large enterprises. Beyond showcasing generative AI’s real-world potential in complex engineering tasks, the project highlights three transformative industry trends:

1. Legacy System Integration Is the Gateway to Industrial AI Adoption

Enterprise transformation efforts are often constrained by the inertia of legacy infrastructure. DevGen.AI demonstrates that AI can move beyond chatbot interfaces or isolated coding tasks, embedding itself at the heart of IT infrastructure transformation.

2. Semantic Intermediation Is Critical for Quality and Control

By shifting the translation paradigm from “code-to-code” to “code-to-spec,” DevGen.AI introduces a bilingual collaboration model between AI and humans. This not only enhances output fidelity but also significantly improves developer control, comprehension, and confidence.

3. Organizational Modernization Amplifies AI ROI

Mike Pizzi, Morgan Stanley’s Head of Technology, notes that AI amplifies existing capabilities—it is not a substitute for foundational architecture. Therefore, the success of AI initiatives hinges not on the models themselves, but on the presence of a standardized, modular, and scalable technical infrastructure.

From Intelligent Tools to Intelligent Architecture

DevGen.AI proves that the core enterprise advantage in the AI era lies not in whether AI is adopted, but in how AI is integrated into the technology evolution lifecycle. AI is no longer a peripheral assistant; it is becoming the central engine powering IT transformation.

Through DevGen.AI, Morgan Stanley has not only addressed legacy technical debt but has also pioneered a scalable, replicable, and sustainable modernization framework. This breakthrough sets a precedent for AI-driven transformation in highly regulated, high-complexity industries such as finance. Ultimately, the value of enterprise AI does not reside in model size or novelty—but in its strategic ability to drive structural modernization.

AI-Driven Software Development Transformation at Rakuten with Claude Code

June 30, 2025

Rakuten has achieved a transformative overhaul of its software development process by integrating Anthropic’s Claude Code, resulting in the following significant outcomes:

Claude Code demonstrated autonomous programming for up to seven continuous hours in complex open-source refactoring tasks, achieving 99.9% numerical accuracy;
New feature delivery time was reduced from an average of 24 working days to just 5 days, cutting time-to-market by 79%;
Developer productivity increased dramatically, enabling engineers to manage multiple tasks concurrently and significantly boost output.

Case Overview, Core Concepts, and Innovation Highlights

This transformation not only elevated development efficiency but also established a pioneering model for enterprise-grade AI-driven programming.

Application Scenarios and Effectiveness Analysis

1. Team Scale and Development Environment

Rakuten operates across more than 70 business units including e-commerce, fintech, and digital content, with thousands of developers serving millions of users. Claude Code effectively addresses challenges posed by multilingual, large-scale codebases, optimizing complex enterprise-grade development environments.

2. Workflow and Task Types

Workflows were restructured around Claude Code, encompassing unit testing, API simulation, component construction, bug fixing, and automated documentation generation. New engineers were able to onboard rapidly, reducing technology transition costs.

3. Performance and Productivity Outcomes

Development Speed: Feature delivery time dropped from 24 days to just 5, representing a breakthrough in efficiency;
Code Accuracy: Complex technical tasks were completed with up to 99.9% numerical precision;
Productivity Gains: Engineers managed concurrent task streams, enabling parallel development. Core tasks were prioritized by developers while Claude handled auxiliary workstreams.

4. Quality Assurance and Team Collaboration

AI-driven code review mechanisms provided real-time feedback, improving code quality. Automated test-driven development (TDD) workflows enhanced coding practices and enforced higher quality standards across the team.

Strategic Implications and AI Adoption Advancements

From Assistive Tool to Autonomous Producer: Claude Code has evolved from a tool requiring frequent human intervention to an autonomous “programming agent” capable of sustaining long-task executions, overcoming traditional AI attention span limitations.
Building AI-Native Organizational Capabilities: Even non-technical personnel can now contribute via terminal interfaces, fostering cross-functional integration and enhancing organizational “AI maturity” through new collaborative models.
Unleashing Innovation Potential: Rakuten has scaled AI utility from small development tasks to ambient agent-level automation, executing monorepo updates and other complex engineering tasks via multi-threaded conversational interfaces.
Value-Driven Deployment Strategy: Rakuten prioritizes AI tool adoption based on value delivery speed and ROI, exemplifying rational prioritization and assurance pathways in enterprise digital transformation.

The Outlook for Intelligent Evolution

By adopting Claude Code, Rakuten has not only achieved a leap in development efficiency but also validated AI’s progression from a supportive technology to a core component of process architecture. This case highlights several strategic insights:

AI autonomy is foundational to driving both efficiency and innovation;
Process reengineering is the key to unlocking organizational potential with AI;
Cross-role collaboration fosters a new ecosystem, breaking down technical silos and making innovation velocity a sustainable competitive edge.

This case offers a replicable blueprint for enterprises across industries: by building AI-centric capability frameworks and embedding AI across processes, roles, and architectures, organizations can accumulate sustained performance advantages, experiential assets, and cultural transformation — ultimately elevating both organizational capability and business value in tandem.

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