Basel III/IV

Basel III was introduced by the Basel Committee on Banking Supervision (BCBS) following the 2008 financial crisis, with phased implementation from 2013 onwards. It established minimum capital ratios (Common Equity Tier 1 of 4.5% of RWA, Tier 1 capital of 6%, Total Capital of 8%), conservation buffer (2.5% CET1), countercyclical buffer (0-2.5%), G-SIB surcharge (1-3.5%), and introduced the leverage ratio and two liquidity standards: the Liquidity Coverage Ratio (LCR, requiring 100% High Quality Liquid Asset coverage of 30-day net cash outflows) and the Net Stable Funding Ratio (NSFR, requiring stable funding to exceed required stable funding over a one-year horizon). Basel IV (the BCBS's "finalization of Basel III," published 2017, implementation date January 1, 2025 for most jurisdictions) substantially revised the standardized approach for credit risk, introduced output floors (requiring RWA calculated using internal models to be at least 72.5% of RWA calculated using standardized approaches), revised operational risk methodology (replacing Advanced Measurement Approaches with the Standardized Measurement Approach), and overhauled market risk capital through the Fundamental Review of the Trading Book (FRTB).

Basel IV represents the most significant restructuring of bank capital calculation infrastructure in a generation. The output floor requirement alone requires banks to run two parallel sets of RWA calculations — internal model-based and standardized — across the entire balance sheet, combining results under complex aggregation rules. The FRTB framework (BCBS 352, 457) replaces the existing VaR-based market risk capital approach with an Expected Shortfall (ES) model at the 97.5th percentile, mandatory Profit and Loss Attribution (PLA) tests to validate internal models, sensitivity-based approaches for standardized capital, and the requirement to distinguish trading book from banking book using prescribed criteria. PLA testing requires banks to compare front-office desk-level P&L against the risk model's hypothetical P&L at daily frequency — this requires tight integration between front-office pricing systems, risk systems, and capital calculation engines, which are typically separate platforms with different data models. The standardized credit risk approach under Basel IV uses more risk-sensitive risk weights but requires granular borrower data (credit ratings, LTV ratios, income verification status) that many banks do not currently collect systematically.

National implementation of Basel IV has proceeded at different rates and with national discretions that create compliance complexity for international banking groups. The US Basel III endgame proposal (NPR published July 2023) applied Basel IV's output floor, FRTB, and credit risk revisions to Category I-IV banks, but faced significant industry pushback leading to a re-proposal process extending implementation timelines. The EU's CRR3 (Capital Requirements Regulation 3) implements Basel IV from January 2025 with specific EU modifications including a partially diverging FRTB implementation and EU-specific discretions on real estate risk weights. UK PRA is implementing Basel 3.1 (its Basel IV equivalent) from January 2026 with separate consultation processes. For internationally active banks, the interaction of these three major jurisdictional implementations — each with different phase-in timelines, national discretions, and reporting requirements — creates a complex regulatory compliance engineering challenge that cannot be solved with a single global capital calculation engine.

We architect Basel IV-compliant capital calculation platforms with parallel standardized and internal model calculation pipelines producing RWA outputs that can be aggregated under the output floor framework, with automated reconciliation and floor breach detection. Our FRTB implementations support desk-level PLA test infrastructure with daily front-office/risk P&L comparison pipelines and automated PLA test pass/fail determination per BCBS criteria. For multi-jurisdiction banking groups, we maintain jurisdiction-specific capital calculation variants within a unified data model, applying national discretions as configurable parameters rather than hardcoded logic to facilitate regulatory change management.

Compliance-Native Architecture Guide

Design principles and a structured checklist for building software that is compliant by default — not compliant by retrofit. Covers data architecture, access controls, audit trails, and vendor due diligence.