What Is a Custom Model Portfolio in a 401(k) Plan?
Somewhere between a single target-date fund and building a portfolio fund by fund, a few 401(k) plans offer a third menu item: a ready-made mix built around a specific strategy.
The short answer
A custom model portfolio inside a 401(k) is a pre-built combination of the plan’s existing funds, assembled around a particular strategy or risk level, that a participant can select as a single unit instead of choosing and weighting individual funds on their own. Unlike a personalized managed account, a model portfolio is typically the same fixed mix for everyone who selects that particular model, rather than one adjusted to an individual participant’s specific data. These portfolios are usually built by an outside investment professional or committee the plan works with, and rebalancing back to the target mix is generally handled automatically once a participant opts in.
Who typically builds these models
Model portfolios aren’t usually built by the plan sponsor directly. Instead, an outside investment advisor, asset manager, or committee the plan works with generally designs each model, selecting which of the plan’s existing funds to include and in what proportions. The plan sponsor still holds responsibility for selecting and monitoring the funds available on the broader menu, including any models offered, as part of its ongoing oversight of the plan’s investment lineup.
How a model portfolio differs from the alternatives
- Versus picking individual funds yourself. Self-directed selection means choosing each fund and its percentage allocation independently, and rebalancing it manually or not at all; a model portfolio bundles that decision into a single, pre-set combination.
- Versus a target-date fund. A target-date fund shifts its mix automatically as a target year approaches, based on age alone. A model portfolio, by contrast, is usually built around a stated risk level or strategy rather than a specific retirement year, and it doesn’t necessarily change its risk profile over time the way a target-date fund’s glide path does, unless the model itself is periodically updated.
- Versus a managed account. A managed account is personalized to the individual using account-specific data; a model portfolio applies the same fixed mix to everyone who picks it, which generally makes it a lower-cost option than a fully managed account, though not necessarily free.
Rebalancing that comes built into the model
One of the practical benefits of a model portfolio is that the funds inside it are periodically brought back to their original target weights automatically, similar to how portfolio rebalancing works more generally, without the participant needing to place trades or track drift between funds manually. The frequency and method of rebalancing depend on how the specific model was designed and can vary between the different models a plan offers.
What to weigh before choosing a model portfolio
Not every model portfolio fits every participant equally well, since the mix is built around an assumed risk level or strategy rather than one person’s actual circumstances. Comparing the description of a given model — including any additional fee layered on top of the underlying funds — against a personal sense of comfort with investment ups and downs is a reasonable starting point, along with checking whether the plan’s disclosure materials explain how and when the model gets rebalanced or updated.
The takeaway
A custom model portfolio offers a middle ground between full self-direction and a fully personalized managed account, bundling a set of the plan’s existing funds into a single, professionally assembled mix with automatic rebalancing. Understanding what strategy a specific model is built around, and how it differs from the plan’s other default and managed options, is the practical way to judge whether it fits.