Why combining indices is becoming a core design technique, and what makes it hard to get right.
What is index blending?
Index blending is the process of combining two or more indices (components) into a single composite index governed by a defined set of weighting and rebalancing rules.
The building blocks can be broad market benchmarks, factor or thematic indices, or sleeves from different asset classes. The result is one index, with one return series, that expresses a specific view or risk profile.
The simplest example is a static 60/40 blend of an equity index and a bond index. More sophisticated approaches use dynamic allocation, such as volatility targeting, risk-based weights or trend overlays, which adjust exposure to each component according to pre-defined, rules-based logic.
The benefits of a multi-asset index blend
A multi-asset index packages exposures to different asset classes into a single, transparent benchmark. The main advantages are:
- Diversification across return drivers. Combining assets with different sensitivities to growth, inflation and rates can smooth the return path and reduce drawdowns relative to a single-asset exposure.
- Precise risk and return targeting. Weights, volatility targets and constraints can be calibrated to achieve a specific objective, from conservative income to growth-oriented outcomes.
- Efficient reuse of existing indices. Established components bring track records and data, so new strategies can be assembled faster than by building from scratch.
- Product flexibility. A single blended index can underpin an ETF, a fund-of-funds benchmark, a structured product, or a model portfolio.
- Transparency and auditability. Rules are documented and systematic, which supports performance attribution and clear communication to clients.
Trends driving index blending
Several forces are driving demand. As headline fees on core exposures compress, differentiation is shifting towards index methodology, and blending is a natural path to a distinctive product.
Asset managers are also building more outcome-oriented and multi-asset solutions, from target-risk to income strategies, that need a benchmark to match. The much-debated “death of 60/40” has added momentum: after 2022, when equities and bonds fell together, many investors began questioning static equity/bond splits and looking to dynamic, broader multi-asset blends with additional diversifiers such as private assets or commodities.
Why blending is difficult to implement
The concept is simple; the operational reality is not. The first challenge is data: components often come from different providers, with different licensing terms, currencies, holiday calendars and pricing times that must be reconciled before a blend can be calculated.
Rebalancing adds a second layer. Each component follows its own schedule and the blend adds another, while index events and corporate actions in a component must flow through to the composite consistently and on time.
Governance compounds the problem. Under benchmark regulation, including the UK and EU Benchmarks Regulations, administrators need documented methodologies, change controls and audit trails. Spreadsheets and bespoke scripts struggle to meet that standard at scale and can be difficult to audit.
How PANTA supports index blending
PANTA’s Index Operating System lets index providers and asset managers define blend methodologies, constraints and rebalancing rules in an intuitive frontend rather than custom code. Teams can bring in data from multiple providers, backtest and iterate on designs, and run calculation and rebalancing within a single environment with detailed audit trails.
The result is that teams spend their time on index design and the underlying investment idea, not on stitching together data and infrastructure.
Conclusion
Index blending turns existing indices into new, bespoke exposures. It offers diversification, precise risk targeting and faster product development, and it fits a market where methodology, rather than fees alone, increasingly sets products apart.
The difficulty lies in execution: reconciling data across multiple providers, managing layered rebalances and meeting governance standards. Firms that pair a clear design philosophy with robust, auditable index technology will be best placed to build multi-asset indices that scale.