Investing in the stock market doesn't require picking individual winners or timing market swings. For most everyday investors, a low-cost S&P 500 index fund provides instant diversification and historic market returns without the stress of active management.
The Fidelity 500 Index Fund (ticker: FXAIX) stands out as one of the most accessible and cost-effective choices available. It mirrors the performance of the S&P 500, giving you fractional ownership in five hundred of the largest publicly traded corporations in the United States. Whether you're opening your first Roth IRA or building a taxable brokerage portfolio, FXAIX serves as a core foundational holding.
Here's a breakdown of how the fund operates, what you'll pay in fees, how it compares to alternatives, and whether it fits your financial goals.
Understanding FXAIX and How It Tracks the Market
FXAIX is a passively managed mutual fund. Instead of employing a team of analysts trying to beat the stock market, the fund managers simply buy and hold the stocks that make up the S&P 500 index in exact proportion to their market capitalization.
When you purchase shares of FXAIX, your money is instantly distributed across major sectors like technology, healthcare, financials, consumer discretionary, and industrials. Mega-cap corporations like Microsoft, Apple, NVIDIA, and Amazon make up the largest weightings in the fund due to their massive market caps.
Because it's market-cap weighted, successful companies that grow larger command a bigger slice of the fund, while struggling companies shrink naturally. You don't have to monitor corporate earnings reports or rebalance your holdings manually. The fund does it automatically.
Expense Ratios and Costs: Why Fees Matter
Fees eat away at compounding returns over decades. One of the primary reasons FXAIX is so popular is its rock-bottom expense ratio of 0.015%.
To put that into perspective, for every $10,000 you invest in FXAIX, you pay just $1.50 per year in management fees. Many traditional mutual funds charge 0.50% to over 1.00% annually, which drains thousands of dollars from your portfolio over a twenty-year horizon.
Fidelity also sets no minimum investment requirement for FXAIX. You can start investing with five dollars, ten dollars, or whatever spare cash you have in your account. This removes the traditional $1,000 or $3,000 barriers common among mutual funds, making institutional-grade indexing accessible to absolute beginners.
Performance History and Realistic Expectations
The S&P 500 has historically delivered an average annualized total return of roughly 10% before inflation over long multi-decade periods. FXAIX tracks this benchmark extremely closely, with minimal tracking error.
Past performance doesn't guarantee future results, and the stock market goes through inevitable downturns. For instance, during bear markets or economic recessions, FXAIX will drop in value right alongside the broader market. If you panic and sell during a market correction, you lock in losses. Success with FXAIX requires a multi-year horizon and the emotional discipline to keep buying when prices fall.
To see official fund data, historical returns, and current fact sheets, check the Fidelity FXAIX Overview.
FXAIX vs. Competitors: Vanguard and Schwab
While FXAIX is an exceptional fund, it isn't the only low-cost S&P 500 game in town. You have equivalent choices from other major brokerages, including:
- Vanguard 500 Index Fund (VFIAX / VOO): Vanguard offers VFIAX (mutual fund) and VOO (ETF), both carrying a matching 0.03% expense ratio. While slightly higher than Fidelity's 0.015%, the difference on a $10,000 portfolio is $1.50 per year—negligible for most investors.
- Schwab S&P 500 Index Fund (SWPPX): Charles Schwab matches Fidelity's 0.015% expense ratio.
If you already custody your accounts at Fidelity, use FXAIX. If your accounts are at Vanguard or Schwab, use their respective equivalents. Avoid crossing brokerages unnecessarily, as some platforms charge transaction fees for buying outside mutual funds.
Common Mistakes Investors Make with Index Funds
Even with a simple fund like FXAIX, investors frequently sabotage their own results through avoidable missteps.
- Tinkering constantly: The entire point of an index fund is buy-and-hold investing. Selling during a 10% market dip to "wait it out" usually results in missing the inevitable rebound.
- Ignoring account types: Holding FXAIX in a tax-advantaged account like a Roth IRA or traditional 401(k) shields your dividends and capital gains from annual taxes.
- Expecting overnight wealth: Index funds are wealth-building engines for decades, not get-rich-quick vehicles. If you need cash within the next two to three years, keep it in high-yield savings accounts or Treasury bills rather than stocks.
For broader perspective on how passive indexing compares to active management, review insights from Morningstar.
Frequently Asked Questions
Can I buy FXAIX as an Exchange-Traded Fund (ETF)?
No. FXAIX is structured strictly as a mutual fund, meaning it prices once per day after the market closes. If you want an S&P 500 ETF traded throughout the day at Fidelity, consider using Fidelity's ETF options or buying an ETF like VOO or IVV.
Does FXAIX pay dividends?
Yes. The companies held within the S&P 500 distribute quarterly dividends. FXAIX collects these dividends and passes them along to shareholders. You can choose to take them as cash or automatically reinvest them to buy fractional shares.
Is FXAIX suitable for retirement accounts?
FXAIX is frequently used as the primary equity holding in retirement portfolios, including IRAs, Roth IRAs, and employer-sponsored plans. Its broad diversification and low costs make it an efficient vehicle for long-term compounding.
What is the difference between FXAIX and total stock market funds like FSKAX?
FXAIX tracks the 500 largest US companies, whereas total stock market funds like FSKAX hold over 3,000 stocks, including mid-cap and small-cap companies. Historically, their returns track each other extremely closely because large-cap stocks dominate the total market's capitalization anyway.
