Updated for the 2026-2027 CFA® Level I curriculum.
Before an investor can build a portfolio, someone has to decide what the building blocks are. That decision is asset allocation, and it starts with defining asset classes correctly. Level I tests whether you can tell a well-defined asset class from a poorly defined one, and whether you understand what makes a class useful for allocation decisions. This note covers both.
Quick Answer
Asset allocation is the process of dividing a portfolio among defined asset classes to meet an investor's risk and return objectives. A useful asset class groups investments with similar risk and return characteristics, stays mutually exclusive from other classes, and adds diversification value through low correlation.
CFA Level I tests your ability to apply a specification checklist (homogeneity, mutual exclusivity, diversification, market coverage, and capacity) to judge whether a proposed grouping qualifies as an asset class. Strategic asset allocation sets long-term target weights based on these classes, not on individual securities.
Key Takeaways About Asset Classes and Asset Allocation
Asset allocation decisions happen at the asset-class level, not the individual security level.
A valid asset class must be relatively homogeneous internally and distinct from other classes.
Low or negative correlation between classes is what creates diversification benefit.
Strategic asset allocation sets long-term target weights tied to the investor's objectives and constraints.
Grouping investments too broadly hides risk differences; grouping too narrowly creates unnecessary overlap.
The specification checklist is testable on its own, separate from questions about specific asset class characteristics.
What You Need to Know for CFA Level I
Be able to define what makes a grouping a legitimate asset class, not just a product label.
Recognize the distinct risk and return characteristics required for a class to stand on its own.
Understand strategic asset allocation as a long-term, policy-level decision.
Know why correlation between classes drives diversification value.
Understand implementation considerations, including cost and capacity constraints.
Identify why overly broad or overly narrow class definitions weaken allocation decisions.
Defining Asset Classes for Allocation
An asset class is a group of investments that share similar risk and return characteristics and behave similarly in the market. Before an investor allocates capital, the classes themselves need to be specified clearly. This step happens early in the portfolio planning process, right after the investment policy statement sets objectives and constraints.
CFA Level I uses five criteria to judge whether a proposed grouping qualifies as a useful asset class:
Homogeneity. Assets within the class should share similar characteristics.
Mutual exclusivity. Classes should not overlap with each other.
Diversification. The class should add diversification value, meaning it is not perfectly correlated with other classes.
Market coverage. As a group, the defined classes should account for a large portion of investable wealth.
Capacity. The class should be large and liquid enough to absorb a meaningful investment.
A grouping that fails these criteria is not a useful asset class, even if it has a common label.
Distinct Risk and Return Characteristics
Two groupings only count as separate asset classes if they behave differently enough to matter for allocation. If two groups move together and share the same drivers of return, treating them as separate classes adds complexity without adding insight.
This is different from describing the specific risk and return traits of equities, bonds, or real estate in detail. That level of detail belongs to a separate topic. Here, the test is simpler: does this grouping behave distinctly enough from other groupings to justify a separate allocation decision?
Strategic Asset Allocation
Strategic asset allocation is the process of setting long-term target weights for each asset class based on the investor's objectives, constraints, and expectations about long-run risk and return. It is a policy decision, made at the portfolio level, and it is set before any individual security is selected.
Strategic asset allocation answers one question: given this investor's goals and constraints, how should capital be divided among asset classes over the long term? It does not answer which specific stock or bond to buy. That is security selection, a separate decision made after the strategic allocation is set.
Because strategic allocation is a long-term target, it typically changes only when the investor's objectives, constraints, or capital market expectations change meaningfully. Short-term market movements do not, by themselves, justify changing the strategic allocation.
The Role of Correlations
Correlation measures how two asset classes move relative to each other. A correlation near +1 means the classes move together. A correlation near -1 means they move in opposite directions. A correlation near 0 means the two classes move independently.
Diversification benefit comes from combining asset classes with low or negative correlation. If two classes always move together, combining them does little to reduce portfolio risk. If they move independently or oppositely, combining them can reduce overall portfolio volatility without necessarily sacrificing expected return.
This is why the specification checklist includes a diversification criterion. An asset class that behaves identically to an existing class does not earn its place in the allocation, even if it has a different name.
Implementation Considerations
Once asset classes are specified and strategic weights are set, implementation questions follow. These include:
Cost. Some asset classes carry higher transaction costs, management fees, or tax burdens.
Liquidity. Some classes trade quickly with low friction, others do not.
Capacity. A class needs to be large enough to accept a meaningful allocation without moving prices against the investor.
Availability of vehicles. Not every asset class has efficient investment vehicles for every investor.
These considerations affect how allocation targets get implemented, but they do not change the underlying logic of defining the classes correctly first.
Why Overly Broad or Narrow Classes Weaken Decisions
Defining classes too broadly hides meaningful risk differences. Lumping all fixed income together, for example, ignores the different risk and return drivers behind government bonds, high-yield corporate bonds, and inflation-linked bonds. An investor allocating to one broad "bonds" class may unknowingly take on more credit risk or duration risk than intended.
Defining classes too narrowly creates the opposite problem. Splitting a single market into many overlapping micro-categories adds complexity without adding diversification value, since the categories move together and share the same underlying risk drivers. This violates the mutual exclusivity and diversification criteria at the same time.
Level I questions often test this by presenting a proposed set of asset classes and asking whether the grouping is appropriate. Applying the five-part checklist is the fastest way to answer correctly.
Asset-Class Specification Checklist
Use this checklist whenever a question asks you to evaluate a proposed asset class or grouping.
Criterion | Question to Ask |
|---|---|
Homogeneity | Do assets within the class share similar risk and return drivers? |
Mutual exclusivity | Does this class overlap with another proposed class? |
Diversification | Does this class have low or negative correlation with other classes? |
Market coverage | Do the proposed classes together cover a large share of investable wealth? |
Capacity | Is the class large and liquid enough to absorb a meaningful allocation? |
Worked Example
Scenario: An advisor proposes the following groupings for a client's strategic asset allocation:
Group A: Large-cap U.S. equities
Group B: Small-cap U.S. equities
Group C: U.S. investment-grade corporate bonds
Group D: U.S. high-yield corporate bonds
The advisor initially suggests combining Groups A and B into one "U.S. equities" class and combining Groups C and D into one "U.S. bonds" class.
Step 1: Check homogeneity within each combined group
Large-cap and small-cap equities share market risk but differ in volatility and return drivers. Investment-grade and high-yield bonds differ sharply in credit risk and typical correlation to equities during stress periods. Combining them hides these differences.
Step 2: Check mutual exclusivity
Keeping the four groups separate avoids overlap. Each group targets a distinct segment.
Step 3: Check diversification value
High-yield bonds often behave more like equities during downturns than like investment-grade bonds. Combining Groups C and D into one "bonds" class would understate this correlation risk.
Step 4: Check market coverage and capacity
All four groups are large, liquid U.S. markets with ample capacity to absorb institutional or individual allocations.
The four original groups (A, B, C, D) pass the specification checklist better than the two combined groups. Combining large-cap with small-cap equities, or investment-grade with high-yield bonds, hides meaningful risk and return differences and understates diversification needs. The advisor should keep the four groups separate for strategic allocation purposes.
Common Exam Traps
Using overlapping asset classes. If two proposed classes share the same underlying risk exposure, they fail the mutual exclusivity test even if they carry different names.
Defining classes only by product label. A grouping labeled "alternative investments" is not automatically a valid asset class. The label does not guarantee homogeneity or distinct risk and return characteristics.
Ignoring correlation and diversification. A class that moves in lockstep with an existing class adds little value, regardless of how it is described in marketing materials.
Confusing strategic allocation with security selection. Strategic allocation sets target weights across classes. Choosing a specific stock, bond, or fund within a class is a separate, later decision.
Practice Questions
An investment committee proposes three asset classes for a strategic allocation: domestic government bonds, domestic corporate bonds, and domestic equities. A member argues that government and corporate bonds should be combined into a single "domestic bonds" class because both are debt instruments issued in the same currency.
Which response best evaluates this proposal using the asset-class specification criteria?
Combine the two bond groups, since both are debt instruments and share currency risk.
Keep the two bond groups separate, since they differ meaningfully in credit risk and may not move together during stress.
Combine all three groups into one class, since domestic government bonds, corporate bonds, and equities are all issued by domestic entities.
Correct Answer: B
Government bonds and corporate bonds differ in credit risk. Corporate bonds carry default risk that government bonds (in most developed markets) do not. During periods of financial stress, corporate bond spreads widen while government bond yields often fall, meaning the two groups do not move together. Keeping them separate respects the homogeneity and diversification criteria.
Option A: This choice relies only on the shared debt-instrument label and currency, ignoring the credit risk difference that drives distinct return behavior.
Option C: This choice combines asset classes with fundamentally different risk and return drivers (equity risk versus fixed income risk), which fails the homogeneity criterion badly.
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FAQs About Asset Classes and Asset Allocation
What is asset allocation in simple terms?
Asset allocation is the decision of how much of a portfolio to invest in each asset class, such as equities, bonds, and real estate, based on the investor's objectives and constraints.
What is the difference between strategic asset allocation and security selection?
Strategic asset allocation sets long-term target weights across asset classes. Security selection is the later decision of choosing specific securities within each class.
Why does correlation matter when defining asset classes?
Low or negative correlation between classes is what creates diversification benefit. A class that moves identically to an existing class adds little value to the allocation.