Time-weighted return measures what an investment earned per dollar held, independent of how much money was in it at any moment. It is calculated by cutting the holding period at every contribution and withdrawal, computing each slice's return on its own, and multiplying those slices together — which is why it is also called a chain-linked return.
Why deposits are divided out
A contribution changes a balance without the investment having earned anything. Chain-linking isolates each slice between flows, so a deposit affects which slice you are in but never the return attributed to that slice. The result describes the investment, not the investor.
That makes it the standard basis for comparison. A fund's published performance is time-weighted, and an index has no cash flows at all, so a time-weighted figure is the one that can be set beside either without the comparison being distorted by deposit timing.
Why it can differ sharply from your own result
Your personal result depends on when you added money; Money-Weighted Return captures that and time-weighted return deliberately does not. A gap between the two is normal and informative: it says the timing of contributions helped or hurt relative to simply having been invested throughout.
What it needs to be computable
Time-weighted return needs the position valued at every cash-flow date, not just today. That means price history covering the whole span. Where that history is unavailable — a security never priced, or a date before the available record — the figure cannot be produced, and no approximation is substituted for it.
Reading the number
The chain-linked figure is cumulative over the whole span. Annualizing it compresses that into a per-year rate, which is comparable across positions held for different lengths of time but, over a short span, extrapolates aggressively from very little.
NetWorthy computes time-weighted return per holding, from your recorded history and the price record for that security. It describes past performance and is not a forecast.
See also Cost Basis.