What Is a Mutual Fund?

How a Mutual Fund Works

You send your money in. The fund pools it with everyone else's. The manager invests it according to the objective spelled out in the prospectus — that's the legal document the fund has to give you, and most people never read it. A US stock fund buys American stocks. A bond fund buys bonds. An international fund buys foreign equities. Whatever the fund earns or loses, you share in proportionally to how many shares of the fund you own.

One detail surprises people. Mutual funds, unlike ETFs, do not trade on a stock exchange during the day. You can place a buy order at 10am, but it won't actually execute until the market closes at 4pm and the fund calculates its net asset value (NAV) — the total value of everything the fund owns, divided by the number of shares outstanding. One price per day. For long-term savers this matters very little. For someone who wants to react to intraday news, it matters a lot, and they should probably be using ETFs instead.

Types of Mutual Funds

Most working families don't need more than three of these. A broad US stock index fund, a total bond fund, and maybe an international fund — that is a complete portfolio for most people. Everything else is fine-tuning.

Active vs. Passive Management

This is the most important distinction in the whole category, and it's the one that costs families the most when they get it wrong.

• Active funds employ a portfolio manager whose job is to pick stocks and beat the market. To pay for the research team, the analysts, the trading desks, and the manager's salary, the fund charges higher fees — usually 0.50% to 1.50% per year. The uncomfortable part: over any 15-year period, roughly 85% to 90% of actively managed funds underperform their benchmark index. The handful that outperform rarely repeat the trick over the next 15.
• Index funds don't try to beat anything. They simply hold every stock in an index (the S&P 500, for example) in proportion to its market capitalization. No stock picking. No market timing. Annual fees run from about 0.03% to 0.20%. Over long horizons, that boring, mechanical approach beats most active managers after fees.

Peter Lynch ran the Fidelity Magellan Fund and put up one of the rare active records that genuinely outran the market. Lynch himself was the first to say his result was an exception, not a template, and that most investors would do better in a low-cost index fund. The lesson most savers eventually arrive at: loyalty to a fund manager you've never met is not a strategy. The index version of the same category usually wins out, year after quiet year.

Fees: The Quiet Drag on Your Returns

Fund fees compound. That is the part most people miss. They look at a 1% expense ratio and think one percent is one percent, the way you'd think about a sales tax. It isn't. It's one percent every year, deducted from a balance that should be growing, and the growth that fee prevents also doesn't compound. Over a working lifetime that gap is the difference between a comfortable retirement and a tight one.

Expense Ratio

The annual fee charged as a percentage of fund assets, deducted automatically from the fund's returns. A fund with a 1.0% expense ratio that earns 8% gross delivers 7% to investors. Over 30 years, the difference between a 0.10% expense ratio and a 1.0% expense ratio on a $100,000 investment works out to roughly $150,000 in lost returns (I've watched clients spend more time picking between two near-identical large-cap funds than on the rest of their financial plan combined, and the expense ratio is almost always the thing they should have been looking at). That gap doesn't show up on any statement. It shows up in what isn't there at the end.

Sales Loads

• Front-end load — a commission paid when you buy, typically 3% to 5%. A 5% front-end load means $5,000 of a $100,000 investment goes straight to the salesperson, not into the market. You start at $95,000.
• Back-end load — a commission paid when you sell, usually declining if you hold the fund for 5 to 7 years.
• No-load — no sales commission at all. Vanguard, Fidelity, and Schwab all offer extensive no-load lineups, and for most investors a no-load fund is the right choice. Full stop.

12b-1 Fees

Annual marketing and distribution fees of up to 1.0%, tucked inside the expense ratio. These cover advertising and broker compensation, not portfolio management, and they offer no benefit to you as a shareholder. If you see one on a fund prospectus, that is a reason to keep looking.

Mutual Funds vs. ETFs

The gap between mutual funds and ETFs has narrowed a lot over the last decade. For most purposes, ETFs are now the more efficient choice, thanks to lower fees, intraday trading, and better tax treatment in a taxable account. But mutual funds still hold a few real advantages worth knowing.

• Automatic investing. Most fund companies let you set up automatic monthly investments of fixed dollar amounts — $200 on the 15th, every month, without you having to think about it. That makes mutual funds well-suited to systematic retirement saving. Boring is good.
• No bid-ask spread. Mutual funds transact at NAV. There is no spread to absorb. ETFs carry a bid-ask spread that can add up for small, frequent purchases.
• Fractional shares. You can invest exact dollar amounts in mutual funds ($500, $1,000, $137.42 if you want). ETFs traditionally required whole shares, though many brokers now offer fractional ETF shares too.
• Retirement accounts. Most 401(k) plans offer mutual funds, not ETFs. If your plan includes a low-cost S&P 500 index fund, that is almost always the right place to start.

How to Evaluate a Mutual Fund

1. Expense ratio. Below 0.50% for an active fund. Below 0.20% for an index fund. Below 0.05% for a broad-market index fund. Anything higher needs a clear reason.
2. Performance versus benchmark. Compare the fund's 5-year and 10-year returns to its benchmark index, not to other funds. Persistent underperformance is a signal to switch to the index version of the same category.
3. Manager tenure. For an active fund, ask how long the current manager has been running the strategy. A strong 10-year record means very little if the person who built it walked out the door last year.
4. Turnover ratio. The rate at which the fund trades its own holdings. Turnover above 100% means high internal trading costs and reduced tax efficiency in a taxable account.
5. Minimum investment. Some funds still require $1,000 to $3,000 to open a position. Many index funds now have low or zero minimums — that's where most new savers should be looking.

The Bottom Line

For long-term investors who want something simple and effective, a low-cost total stock market index fund — Vanguard's VTSAX or Fidelity's FSKAX, for example — paired with a total bond market fund gives you diversified exposure to the entire US market at minimal cost. The approach is not exciting. It has, however, outperformed most alternatives over 10-year-plus horizons, and that is the only horizon that matters for retirement money.

For active traders who pick individual stocks, mutual funds serve a different purpose: a stable core around which higher-conviction positions can be built. A common arrangement keeps 60% to 80% of the portfolio in low-cost index funds and uses the remaining 20% to 40% for active stock picks. The base is quiet. The satellite portion can be louder. Over decades the quiet base is what does most of the heavy lifting, and most investors find that out only after they've spent years thinking it was the other way around.

See also: ETFs · What Are Dividends? · What Is the P/E Ratio? · Peter Lynch · Value Investing