Computed by the MarketHeist portfolio engine · Updated 2026-10-10
Most ETFs are young. This page shows, for 26 popular funds, how far back their monthly total returns reach once an older mutual fund or index is spliced on, and how closely that older fund actually tracked the ETF while both existed.
Each row links to a page with the full splice: which fund supplies which months, the correlation, tracking error and tracking difference of every proxy against the ETF, a side-by-side of the ETF's own years versus the extended years, and how the fund did in each major US stock-market decline since 1985.
"Proxy fit" is the worst grade among the proxies that supply months. Close means the proxy followed the ETF tightly. Approximate means it followed it with a visible gap. Category stand-in means the proxy is in the same category but is not a tracker, so the extended years are a stress test of the category rather than the fund's own history.
What about ETFs without a proxy?
An ETF with no older fund to splice starts at its own inception. Gold is the example: GLD's monthly data starts in Dec 2004 and there is no usable older gold series in our data, so a gold backtest cannot reach further back than that here.
Methodology
Source
Yahoo Finance via MarketHeist, monthly adjusted close (dividends reinvested), to the last complete calendar month.
Splice rule
Each month uses the youngest fund that has data for it; returns are spliced, not prices (dividends reinvested via adjusted close).
Grades
Computed from each proxy's correlation, tracking error and volatility ratio against the ETF over the months both exist; thresholds are on every fund page.
Numbers
Every figure is computed by the MarketHeist portfolio engine; no figure is written by hand and no language model is involved.
Historical simulation, not investment advice. Past returns, including spliced proxy returns, do not predict future results.