Portfolio Turnover Is A Cost You Never Authorize

Every trade a fund makes inside its portfolio has a cost, and shareholders bear it. These transactions are never presented for approval and never appear as a line item.

What turnover measures

Turnover is a published figure describing how much of a fund's portfolio was replaced over a year. It is calculated from the fund's own buying and selling, not from shareholder activity.

A low figure describes a portfolio whose holdings mostly stayed put. A high one describes a portfolio that was substantially rebuilt within the year.

The number says nothing about whether the trading was wise. It says only how much activity occurred, which is the input to the cost that follows.

Trading has three separate costs

The first is explicit: brokerage commissions paid to execute orders. These are real expenses of the fund and reduce its assets when incurred.

The second is the spread, the gap between what a buyer pays and a seller receives. It is not itemized anywhere but is paid on every purchase and every sale.

The third is market impact, the price movement caused by the order itself. A large fund buying a modestly traded security pushes the price against itself while filling.

Why none of it lands in the expense ratio

The expense ratio is defined to capture ongoing operating expenses. Transaction costs are treated as part of the cost basis of the securities rather than as operating charges.

The result is an accounting boundary rather than a judgment about importance. Two funds can report identical ratios while one incurs far more trading cost than the other.

Commissions are disclosed elsewhere in fund reports, and turnover is disclosed in the prospectus, but the two live in different documents and are rarely read together.

Index funds are not automatically low-turnover

A fund tracking a broad, capitalization-weighted index trades relatively little, because the index adjusts itself as prices move rather than requiring transactions.

Narrower or rules-based indexes are different. An index that reconstitutes on a schedule, or one that screens holdings by changing characteristics, forces its trackers to trade at defined moments.

Funds that select by size, sector or specific themes therefore carry structural turnover. The activity comes from the index rules rather than from anyone's discretion.

How turnover shows up in what an investor receives

Trading costs reduce the fund's assets, which flows straight into the daily net asset value. The effect is a slower drag rather than an event.

Selling appreciated holdings also generates gains that funds must distribute to shareholders, which affects investors holding in taxable accounts. Treatment varies by circumstance and belongs with a tax professional.

Reading turnover next to the expense ratio therefore gives a fuller picture than either alone. One describes what is charged, the other describes activity whose costs are charged without ever being named.