Compare Your Portfolio to the S&P 500 or SPY and See the Gap Over Time
Knowing your holdings went up is not the same as knowing how they did against the market. Indexes models your portfolio as a weighted index and shows the gap to the S&P 500, in a backtest and going forward.
Educational only · Never places a trade
In short
To compare your portfolio to the S&P 500 with Indexes, you model your holdings as a weighted index, then measure that index against the benchmark both historically and going forward. You enter each holding and its weight so your portfolio becomes a single index, and Indexes backtests it against real historical data, showing hypothetical historical performance beside the S&P 500 so you can see where the two diverged over past periods. From there you track the index over time and read the running gap to the benchmark. This is informational and educational analysis, not investment advice and not a claim about beating the market; it simply shows the relationship between your index and the benchmark. Indexes places no trades, connects to no brokerage, and holds no money, so there is no account minimum and it works globally. Past performance does not guarantee future results.
Why it fits
Investors who want to see how their holdings stack up against the S&P 500 over time, modeled as an index and measured as analysis.
Your holdings as one index
Weight your holdings and Indexes treats them as a single index, so the comparison is portfolio versus benchmark rather than ticker by ticker.
See the gap, past and present
Backtest against the S&P 500 as hypothetical historical performance, then track the running gap over time, so you always see your index in context.
Context, not a verdict
Indexes shows the relationship to the benchmark as analysis, never advice or a claim about beating the market. No trades, no brokerage, no account minimum.
Questions
Comparing your portfolio to the S&P 500, answered
How do I compare my portfolio to the S&P 500?
Model your holdings and weights as a single index, then chart it against the S&P 500 over identical dates using the total return version of the index. Comparing ticker by ticker is not a comparison. The portfolio has to be one weighted line before the gap means anything.
Is the S&P 500 a good benchmark for my portfolio?
Only if your portfolio is essentially US large-cap stocks. It holds 500 large US companies and nothing else, so it is the wrong reference for holdings that include bonds, small caps, international shares or REITs. Our portfolio benchmark guide maps each kind of portfolio to the index that fits it.
Should I use the S&P 500 price index or total return index?
Total return, always. The price index excludes dividends, which have been a substantial part of long-run S&P 500 returns. Benchmarking against the price version quietly gives your portfolio a head start of roughly the dividend yield each year and makes the comparison meaningless.
Why does my portfolio trail the S&P 500 in some years and beat it in others?
Usually because the portfolio holds things the index does not. Any bond, international or small-cap exposure will lag in a year when US large caps lead and cushion the fall when they drop. That pattern is your asset allocation showing up, not evidence about your stock selection.
What if my portfolio holds bonds as well as stocks?
Then the S&P 500 alone cannot judge it, and you need a blended benchmark weighted to your allocation. The standard 60/40 version is 60% S&P 500 plus 40% Bloomberg US Aggregate, and the 60/40 benchmark guide walks through building and calculating it.
Should I compare my portfolio to SPY or to the S&P 500 index?
Use the index itself when you can, and SPY when you cannot. SPY is an ETF tracking the S&P 500, so it carries a small expense ratio and tiny tracking differences that the index does not. Over one year the gap is negligible. Over twenty years, comparing against SPY instead of the total return index quietly flatters your portfolio by roughly the fund fee compounded. Either is defensible provided you say which one you used and stay consistent.
How do I compare two portfolios against each other?
Model each one as its own weighted index, then chart both over identical dates. The comparison only means something if the start date, the end date and the dividend treatment match, because shifting a start date by a few months across a drawdown can reverse which portfolio looks better. Comparing portfolios holding by holding tells you almost nothing, since weights drive most of the difference in outcome.
How much should my portfolio trail the S&P 500 before I worry?
There is no threshold that means something on its own, because the honest answer depends on what you own. A portfolio that is 40% bonds should trail US large caps in a strong equity year, and if it did not, that would be the surprising result. What is worth investigating is a persistent gap against a benchmark that genuinely matches your allocation, measured over several years rather than one. Judge the construction, not a single number.
How often should I compare my portfolio to the benchmark?
Quarterly is frequent enough for most people, and annually is defensible. Checking more often mainly generates noise: daily and weekly gaps against an index are dominated by random variation rather than anything about your decisions, and watching them closely tends to prompt trading that costs more than it saves. Set a fixed review date and use the same benchmark and dividend treatment every time.
How do I compare two portfolios against each other?
Model each one as its own weighted index over identical dates, then chart both against the same benchmark rather than against each other. Comparing two portfolios directly hides the reason they differ. Once both are lines against the S&P 500 you can see whether one is genuinely better or simply carrying more equity risk in a rising market.
Should I compare my portfolio to SPY or to the S&P 500 index?
Use the S&P 500 total return index as the benchmark and treat SPY as the investable version of it. SPY tracks the same 500 companies but its returns are net of a roughly 0.09% expense ratio and it can drift slightly from the index intraday. For judging your own selection and weighting, the index is the cleaner reference; for judging whether you should have simply bought the fund instead, SPY is the honest comparison.
What is the difference between an index and a benchmark?
An index is a rules-based measure of a market segment. A benchmark is whichever index you have chosen to judge a specific portfolio against. Every benchmark is an index, but an index only becomes a benchmark once it matches what you actually hold. The S&P 500 is always an index; it is only your benchmark if your portfolio is essentially US large-cap equity.
How often should I compare my portfolio to the benchmark?
Quarterly is enough for a portfolio you intend to hold for years, and annually is defensible. Checking daily mostly measures noise and tends to provoke trading that costs more than it earns. What matters is comparing over the same window you plan to invest across, since a benchmark gap measured over three months tells you almost nothing about a ten year plan.
Why did my portfolio beat the S&P 500 but my account balance still fell?
Because a benchmark comparison is relative and your balance is absolute. Trailing the market by less in a year the market fell is a genuinely better result on a relative basis and still leaves you with less money. Both readings are true. Use the benchmark to judge the construction and use the balance to judge whether the plan fits what you need the money for.
More use cases
Related features
Build your index and see how it backtests
Bundle stocks or crypto into your own weighted index, backtest it against real market history, and track it against the S&P 500 or BTC. Indexes is educational and informational only, and it never places a trade.