A target date fund carries a year in its name and adjusts its own holdings as that year approaches. The adjustment schedule is the product.
One fund holding many funds
These are usually funds of funds, holding other portfolios rather than individual securities, which is how a single holding provides broad exposure across asset classes.
The manager sets the proportions and rebalances them, so the investor does not place trades or make allocation decisions.
This structure is why such funds became the common default in American workplace retirement plans, where most participants make no active choice at all.
The glide path is the defining feature
The mix begins weighted toward assets with higher expected variability and shifts gradually toward those with lower variability as the target year approaches.
The reasoning is that time remaining changes the consequence of a decline, since a portfolio with decades ahead has room to recover and one being drawn down does not.
The path is a schedule, not a reaction to markets. It moves on the calendar regardless of what prices are doing at the time.
To and through are different designs
Some funds reach their most conservative allocation at the target year. Others continue shifting for years afterward, on the assumption the money is spent gradually rather than withdrawn at once.
Two funds with the same year in the name can therefore hold noticeably different mixes at that year, and the difference persists afterward.
The distinction is disclosed in fund documents but not in the name, which is why identical-sounding products behave differently.
The target year is not a retirement date
Selecting a fund by the year one intends to stop working assumes the glide path matches that person's circumstances, which is an assumption rather than a fact.
Someone with other income sources, a different tolerance for variability, or a different spending plan may find the standard path a poor fit.
The fund cannot know any of that. It is designed for a population, and the individual has to judge whether the population's assumptions describe them.
Fees stack in two layers
Because the fund holds other funds, costs can exist at both levels, and how they combine varies between providers and between share classes.
Some providers waive the outer layer, so the total is close to that of the underlying holdings, while others do not.
Reading the stated total expense rather than the top-level figure is the only way to compare two such funds, since the structure differs by manager.