What the Charts Show

These charts show how a portfolio would have grown using real historical data — but "growth" involves several moving parts. Here's what's already baked into the Yahoo Finance data we use, what our simulator adds on top, and how to compare results to a chart you'd find on Fidelity's or Vanguard's website.

What's already in the data

Yahoo Finance is a free financial data service that provides decades of historical prices for funds, ETFs, and stocks. We use its adjusted close price for each fund — not just the share price, but a total return price that already accounts for:

Dividends reinvested — as if every dividend payment bought more shares immediately
Capital gain distributions reinvested — funds pass through realized gains to shareholders annually; these are folded back in
Expense ratios embedded — fund management fees are already reflected in the NAV; we don't subtract them separately

This is the same "total return" baseline used by fund companies for their own growth charts. So our simulator starts from the same place Fidelity does.

What's not in the Yahoo data Taxes. The adjusted close price assumes all proceeds are reinvested with no tax drag whatsoever. For a taxable brokerage account, we layer those calculations on top — which is where the two scenarios below diverge.

One caveat: Yahoo's adjusted prices are designed for ETFs, whose market prices go ex-dividend and need adjustment to reflect total return. Mutual fund NAV already embeds reinvested distributions by definition — so applying the same adjustment double-counts them, overstating historical returns by as much as 80% over long periods. We build our own total-return series from raw prices and distribution records to handle this correctly. See Building Total Return in the Methodology for details.

What the simulator adds

Starting from total-return prices, the simulator applies your chosen parameters month by month. The path is straightforward in a tax-deferred account; a taxable account adds annual tax events at each rebalance.

Tax-Deferred (401k / IRA)

flowchart TD A["Yahoo adjusted close\n— total return price —\ndividends & cap gain distributions\nreinvested; expense ratios embedded"] A --> B["Weight funds by your\nstock / bond allocation"] B --> C["Add monthly contributions\n(new shares at current price)"] C --> D{Rebalance?} D -->|"Annually or\nquarterly"| E["Sell / buy to restore\ntarget split\n— no tax event —"] D -->|Never| F["Let allocation drift"] E --> G{Advisor fee?} F --> G G -->|Yes| H["Deduct annual AUM fee\n(% of portfolio value)"] G -->|No| skip1[" "] H --> J["Final Portfolio Value"] skip1 --> J

Taxable Brokerage Account

flowchart TD A["Yahoo adjusted close\n— total return price —\ndividends & cap gain distributions\nreinvested; expense ratios embedded"] A --> B["Weight funds by your\nstock / bond allocation"] B --> C["Add monthly contributions\n(new shares at current price)"] C --> D{Rebalance?} D -->|"Annually or\nquarterly"| E["Sell / buy to restore target split\ncapital gains tax paid annually\n(20% long-term rate)"] D -->|Never| F["Let allocation drift\n(no annual tax events)"] E --> G{Advisor fee?} F --> G G -->|Yes| H["Deduct annual AUM fee\n(also triggers annual rebalancing)"] G -->|No| skip1[" "] H --> J["Portfolio Value at End Date"] skip1 --> J J --> K["Estimate tax at sale\n= 20% × unrealized gains"] K --> L["After-Tax Value\n= Portfolio Value − Est. Tax at Sale"]

Matching a real-world chart

Growth charts on Fidelity, Vanguard, or Morningstar show total return for a single fund — starting from a lump sum, dividends reinvested, no taxes, no ongoing contributions. Under the hood, the math is surprisingly simple:

The "growth of $10,000" formula

Value on date N = $10,000 × (adjusted close on date N ÷ adjusted close on date 0)

Example: You invest $10,000 when the fund's adjusted close is $50.00. Five years later it's $75.00. Chart value = $10,000 × ($75.00 / $50.00) = $15,000.
That's the whole calculation. Because the adjusted close already folds in reinvested dividends, a single ratio gives you total return — no need to track a growing share count as dividends are paid out.

This is exactly what our simulator does, extended to multiple funds weighted by your stock/bond allocation, with optional monthly contributions and rebalancing on top.

Settings to match a "growth of $10,000" chart Monthly contribution: $0 · Account type: Tax-Deferred · Rebalancing: Never · No advisor fee · Pick one fund at 100% stocks or 100% bonds · Match the start date. The result should be very close.

For a portfolio of multiple funds (e.g. 80% stocks / 20% bonds across three funds), there's no single published chart to compare against — you'd have to blend individual fund charts by weight yourself. Our simulator does this automatically.

The more your settings diverge from that "single fund, tax-deferred, no contributions" baseline — advisor fees, rebalancing, taxable account, ongoing contributions — the less directly comparable any external chart becomes. That's not a flaw in the simulator; it's the nature of modeling a real portfolio rather than a textbook example.

For the technical details behind these calculations — specific formulas, fund tickers, data sources, and the full pipeline — see the Methodology page.