Index Fund
Fonds indiciel in French
Quick definition
An index fund is a fund that simply holds every investment in a market index, such as the broad Canadian or US stock market, instead of trying to pick winners. The goal is to capture the market's return at the lowest possible cost.
Owning the whole market instead of guessing winners
An index fund gives up on the idea of beating the market and settles for owning it. It replicates a published index: the Canadian composite index, the broad US market, international developed markets, or an aggregate bond index. No manager decides which companies will win; the fund holds them all, in proportion, and simply keeps up with its index at minimal cost.
One point of vocabulary trips people up. "Index fund" describes the strategy; the wrapper is separate. Index funds come both as index mutual funds, bought like any mutual fund at a bank or fund company, and as index ETFs, bought through a brokerage. An index ETF is an index fund; so is the index mutual fund at your bank. What matters is the strategy and the fee, not the wrapper.
Why it works
The case for indexing rests on two stubborn facts. The first is cost: index funds charge a fraction of active fees, and that saving compounds year after year exactly the way compound interest does, which the numbers in our MER article show can amount to six figures over an investing lifetime.
The second is the track record of the alternative. The standard scorecard studies that compare active funds to their benchmark index reach the same verdict in market after market: the large majority of actively managed funds underperform their index over 10-year and longer periods, and the few that outperform in one decade are rarely the same ones that outperform in the next. Indexing does not guarantee beating any particular fund; it guarantees you will not trail the market by the size of the fees, which in practice has been enough to land ahead of most professionals.
What indexing does not protect you from
An index fund owns the market, so it owns the crashes too. When the market falls 30%, your index fund falls about 30%, with no manager stepping aside into cash. Indexing removes the risk of picking badly and of paying too much; it removes none of the market's own risk. The strategy only works for people who keep holding through the drops.
Cap-weighted indexes also concentrate where the money is. When a handful of giant companies dominate an index, your "diversified" fund leans heavily on them, and the Canadian composite index has long been concentrated in financials and energy. This is an honest limitation rather than a fatal flaw: it is one reason to hold Canadian, US and international index funds together rather than any single market alone.
Building a simple index portfolio
The classic recipe takes three or four funds: a broad Canadian equity index fund, a US or combined international equity index fund, and a bond index fund, in a mix matching your appetite for risk. Rebalance once a year and keep contributing.
The even simpler modern recipe is a single asset-allocation fund that bundles those same building blocks and rebalances itself, as described in our ETF article. Either route delivers the same essential product: the world's markets, at a cost close to zero, with nothing to predict.
In Canada
Canada has a proud DIY indexing tradition: the "couch potato" portfolio, popularized here over two decades ago, made three-fund indexing a household strategy among Canadian savers long before asset-allocation funds existed.
Where you buy matters in Canada. Index mutual funds sold at bank branches often carry MERs near 1% (as of July 2026), several times the cost of equivalent index ETFs. The bank versions still beat typical active funds, and their automatic-contribution convenience is real, but investors comfortable with a brokerage account keep meaningfully more of the same market return.
Worked example
Aisha invests $500 a month for 30 years. In a broad index portfolio costing 0.2%, a 6% market return becomes 5.8% net, and her contributions grow to roughly $470,000. In a typical active fund costing 2.2%, the same market delivers 3.8% net, or roughly $330,000. To merely match her outcome, the active manager would need to beat the market by about 2 percentage points every year for three decades, a feat the scorecard studies show almost no fund sustains.
Reviewed by Alexandre Bernier, CFP®, CIM®, PFP®·Updated July 2026