Mutual funds explained: NAV, share classes, loads and 12b-1 fees

A mutual fund is a pool of money from many investors that a registered investment adviser invests in stocks, bonds, cash or a mix of them. You buy shares directly from the fund, and when you want out, the fund buys them back. Each share is an equal claim on the whole portfolio and on whatever it earns or loses.

Mutual funds are the default investment in most American workplace retirement plans, and for decades they were the main way small investors got a diversified portfolio. This guide explains how the structure works, how a fund sets its single daily price, the fees that can come with it, including sales loads, share classes and 12b-1 fees, and how to find all of that in the fund's prospectus before you invest.

How a mutual fund works

The fund is a company (legally, an investment company registered with the Securities and Exchange Commission under the Investment Company Act of 1940) whose only business is owning a portfolio. A board of directors oversees it, and an investment adviser makes the day-to-day decisions within the investment objective written in the prospectus.

Open-end means the number of shares is not fixed. When you invest $1,000, the fund issues new shares worth $1,000 and invests the cash. When you redeem, it cancels your shares and pays you, using cash on hand or by selling holdings. That is the key structural contrast with an ETF, whose shares trade between investors on an exchange (see What is an ETF? How exchange-traded funds work), and with a closed-end fund, which issues a fixed number of shares once and then lets them trade on an exchange, often at a premium or discount to NAV.

You make money from a mutual fund in three ways: dividend and interest income the fund passes on, capital gains distributions when the fund sells holdings at a profit, and a rising NAV as the portfolio grows. Most funds let you reinvest distributions automatically in more shares.

NAV and the 4 p.m. price

A mutual fund has one price per business day, its net asset value per share:

Liabilities include fees the fund has accrued but not yet paid, which is how the expense ratio quietly comes out of the price.

The SEC's guide says funds are required to price their shares each business day and typically do so after the major US exchanges close. Under Rule 22c-1, every purchase and redemption must be filled at the NAV next computed after the fund receives the order. In practice, an order that reaches the fund or its broker before the cutoff, usually 4:00 p.m. Eastern Time, gets that evening's NAV; a later order gets the next business day's. You never know your exact price when you place the order.

On the way out, the SEC notes that mutual funds must send payment for redeemed shares within seven days, although many pay sooner, commonly the next business day.

Loads and share classes

Many mutual funds, especially those sold through brokers and financial advisers, charge for the sale. These sales loads pay the broker, like a commission, and come in two forms:

• Front-end load: deducted from your purchase. A 5.75% load on $10,000 means $575 goes to the sales channel and $9,425 is invested.
• Back-end load: charged when you sell. The common version, a contingent deferred sales charge (CDSC), shrinks the longer you hold and may reach zero.

Larger purchases often qualify for lower front-end loads at levels called breakpoints. The SEC's guide notes that funds are not required to offer breakpoints, but if they do, they must disclose them and brokers must apply them. Ask about rights of accumulation (counting your existing holdings in the fund family toward a breakpoint) and letters of intent (committing to invest an amount over time).

A single fund often offers the same portfolio in several share classes that combine these charges differently. The SEC describes the most common ones like this:

Some fund families automatically convert Class C shares into a cheaper class after a set number of years; the prospectus says whether and when.

Working the numbers: which class costs less?

The bigger lesson is the gap at the top of the chart. Over 15 years, the low-cost fund ends about $4,700 ahead of Class A and $5,900 ahead of Class C on the same gross return. Whether a load is worth paying depends on what the advice that comes with it is worth to you. Expense ratios and fund costs: what you pay and how it compounds runs the same math over 40 years.

12b-1 fees and the no-load label

A 12b-1 fee, named after the SEC rule that allows it, is paid out of fund assets every year to cover marketing and distribution and, sometimes, shareholder services. It is part of the expense ratio, so you never see it charged separately.

As of 2026, FINRA Rule 2341 sets the limits for funds sold by brokers: asset-based sales charges may not exceed 0.75% of average net assets a year, service fees may not exceed 0.25%, and aggregate front-end plus deferred sales charges may not exceed 8.5% of the offering price for funds without an asset-based sales charge (lower in some cases). A fund may not be described as no-load if it has a front-end or deferred sales charge, or if its combined sales and service fees exceed 0.25% a year.

No-load does not mean no fees. The SEC points out that a no-load fund can still charge purchase fees, redemption fees (often to discourage short-term trading), exchange fees and account fees, and every fund has operating expenses.

Reading the prospectus fee table

Every mutual fund must give you a prospectus, and its fee table is the single most useful page in it. It has two parts:

1. Shareholder fees, paid directly by you: maximum front-end load, maximum deferred load, redemption fee, exchange fee, account fee.
2. Annual fund operating expenses, paid from fund assets: management fee, 12b-1 fee, other expenses and, for funds of funds, acquired fund fees. The total is the expense ratio. A line for a fee waiver shows a temporary reduction, and the date it ends.

Right after the table, an expense example shows the dollar cost of $10,000 over 1, 3, 5 and 10 years at a standard assumed return, with and without selling, which makes funds with different structures directly comparable. The prospectus also states the investment objective, the principal strategies and risks, past performance against a benchmark, the portfolio turnover rate (a clue to hidden trading costs and future capital gains), and who manages the fund. Fund documents are free on the fund's website and on the SEC's EDGAR system.

Types of mutual funds

• Stock (equity) funds: domestic or international, broad or narrow, growth or value.
• Bond funds: government, corporate, municipal or high-yield, with different interest rate and credit risk.
• Balanced and allocation funds: a stock and bond mix in one fund.
• Target-date funds: an allocation that shifts from stocks to bonds as a target year approaches (see Asset allocation: how stock, bond and cash mixes have behaved).
• Money market funds: short-term, high-quality debt, used to hold cash.
• Index funds: any of the above, built to track an index at low cost (see Index investing: passive vs. active funds and what the data shows).

Pitfalls to avoid

Buying the wrong share class. The same fund can cost very different amounts depending on the class. Ask which classes you're eligible for, including any no-load or institutional class available through a retirement plan or advisory account.

Missing a breakpoint. If you're investing near a breakpoint, or already hold other funds from the same family, ask whether you qualify for a lower load.

Buying just before a capital gains distribution. In a taxable account you get part of your money back as a taxable payment. Funds usually estimate distributions in the autumn.

Treating past performance as a promise. The SEC reminds investors that past performance does not predict future returns; it says more about how volatile a fund has been.

Ignoring turnover. A fund that replaces most of its portfolio each year pays trading costs that are not in the expense ratio and tends to distribute more taxable gains.

How Finabase helps

Mutual funds have symbol pages like stocks and ETFs, with a chart of the daily NAV and the fund's dividend and distribution history on the Dividends & splits tab. The comparison tool shows several funds' period returns side by side and on one rebased chart, and portfolios track what you own at current prices with history, allocation and dividend reports. To compare fees and loads across thousands of funds, the SEC's Investor.gov points investors to the free FINRA Fund Analyzer. Finabase does not sell funds or hold accounts.

Frequently asked questions

When is a mutual fund's price set?

Once each business day, usually after the 4:00 p.m. Eastern close. Orders received before the fund's cutoff get that day's NAV; later orders get the next day's.

Can you lose money in a mutual fund?

Yes. Mutual funds are not insured or guaranteed by the FDIC or any government agency, and their NAV falls when the holdings fall. Money market funds aim to keep a stable value but can still lose money.

What is the difference between a load and a no-load fund?

A load fund charges a sales commission when you buy or sell; a no-load fund does not, and under FINRA's rule may charge no more than 0.25% a year in combined 12b-1 and service fees. Both charge annual operating expenses.

How many share classes can one fund have?

There's no fixed number. Many broker-sold funds offer A, C and institutional classes, and some have a dozen. Every class owns the same portfolio; only the charges differ.

Summary

A mutual fund pools investors' money into one professionally managed portfolio and deals with its shareholders directly: it issues and redeems shares every business day at a single net asset value set after the close, under forward-pricing rules that give everyone the same price. Its costs come in two layers, shareholder fees such as sales loads and annual operating expenses including 12b-1 fees, packaged into share classes that suit different holding periods. The prospectus fee table shows all of it in a standard format, and a few minutes with it, plus a fee calculator, can reveal differences worth thousands of dollars over a lifetime of investing.