Every broker's performance number lies to you (differently)

Last reviewed 9 September 2026.

You added £10,000 to your account in January, the market went up, and your broker says you're up 4.1%. Your friend added the same £10,000, made the identical trades, and her broker says she's up 6.8%. One of you is not lying, and neither is a broker malfunctioning. The gap is almost always the broker return calculation itself — the formula and the assumptions each platform bakes into the single percentage it chooses to show you.

This matters most when you deposit or withdraw money mid-year, which nearly everyone does. Cash flows are exactly where return formulas diverge. A figure that looks great can be an artefact of good timing rather than good picking; a figure that looks mediocre can be hiding genuinely strong selection. If you run two, three or four brokers — the situation StackViewer is built for — you cannot simply add the percentages up or compare them side by side. They are measuring different things.

The three choices behind every return number

Before naming brokers, learn the maths by hand. Every displayed return answers three questions, and the answers determine the number. Do this once and you will never be confused by a dashboard again.

Choice 1: does it remove the effect of your deposits? Say you start the year with £10,000, it grows to £11,000 by June (a genuine +10% on your investing), and then you deposit a fresh £10,000. You end December at £21,500. A naïve calculation — end value minus everything you put in, divided by what you put in — gives (£21,500 − £20,000) / £20,000 = 7.5%. But your investing only ever produced 10% in the first half and a small move after. The 7.5% is diluted by the late deposit that never had time to grow. This is the core problem.

Time-weighted return (TWR) fixes it by breaking the year at every cash flow, computing the growth of each sub-period, and chaining them together, so deposits and withdrawals cannot distort the result. It answers: how good were the investment decisions? That is the number you compare against the S&P 500. Money-weighted return (IRR) does the opposite on purpose — it weights periods by how much money was actually at work, so it answers: what did I personally earn given my timing? Neither is superior; they answer different questions. We unpack the full worked example in TWR vs IRR: which return number is telling the truth.

Choice 2: are dividends and fees included? A "price return" ignores dividends; a "total return" reinvests them. Over a decade, dividends can be a third of total equity return, so this is not a rounding error. Likewise, some figures are gross of fees and commissions, some are net. A platform that shows total return net of fees will always look worse than one showing price return gross of fees, for the identical holdings.

Choice 3: what period, and what start value? "Since inception", "this year", "trailing 12 months" and "since you opened this position" produce wildly different numbers. A default window that starts at a market low flatters everything; one that starts at a peak does the reverse. None of this is manipulation — it is just unstated defaults.

How five named brokers actually calculate it

Here is what each broker's own help documentation says about the return it displays, checked as of 2026-09-10. Brokers change methodology and wording without warning, so treat these as the documented default at the review date and always confirm against the linked page for your own account. Where a broker exposes more than one figure, we describe the headline default a typical user sees.

Fidelity. Fidelity's performance display for retail accounts is documented as a time-weighted rate of return that includes reinvested dividends and interest and is net of commissions and fees, per Fidelity's own "How is my performance calculated?" help content. Verified against Fidelity's help centre (fidelity.com/customer-service, performance methodology article) as of 2026-09-10. Practical consequence: Fidelity's headline percentage is broadly benchmark-comparable, and deposits do not flatter or dilute it.

Vanguard. Vanguard's "Personal performance" tool is documented as showing a dollar-weighted (money-weighted / IRR) return by default, which Vanguard states reflects the effect of the timing and size of your own transactions. Verified against Vanguard's help documentation (investor.vanguard.com, personal performance / rate of return article) as of 2026-09-10. Practical consequence: a Vanguard "personal return" is not directly comparable to an index — it deliberately reflects your cash-flow timing.

Charles Schwab. Schwab documents multiple performance views; its account performance tooling exposes a personal rate of return that is money-weighted, and separately provides time-weighted views in some reports. Verified against Schwab's help content (schwab.com, "understanding your rate of return" / performance reporting) as of 2026-09-10. Practical consequence: which Schwab number you're looking at matters — the default personal return reflects your deposits, while report-level TWR does not.

Robinhood. Robinhood's app historically shows a portfolio value chart and a headline gain that is closer to a net-of-deposits change in value rather than a formal time- or money-weighted rate of return; Robinhood's own support material frames the figure around total return and portfolio value change. Verified against Robinhood's help centre (robinhood.com/support, "how is my return calculated / total return") as of 2026-09-10. Practical consequence: Robinhood's percentage can be pushed around by deposits and by the chart window selected, so it is the least benchmark-comparable of the five without adjustment.

Interactive Brokers (IBKR). IBKR's performance reporting (PortfolioAnalyst) documents a time-weighted return method as its standard performance measure, and also offers a money-weighted option, with clear method labelling. Verified against Interactive Brokers' documentation (interactivebrokers.com, PortfolioAnalyst performance methodology) as of 2026-09-10. Practical consequence: IBKR is the most transparent of the five about which method it is showing, and its default TWR is benchmark-comparable.

Where each broker beats StackViewer's own view. In fairness — and because honesty is the point of this post — two of these brokers do things StackViewer does not. First, IBKR's PortfolioAnalyst lets you switch between time-weighted and money-weighted at will and exports institutional-grade, method-labelled reports; that native flexibility and export depth is genuinely better than what we surface for IBKR-only users. Second, Fidelity and Schwab settle and reconcile figures on their own books in near real time, so their intraday numbers are authoritative to the cent for that account, whereas StackViewer values roughly every 30 minutes and is explicitly not real-time. If you only hold one broker and you want the broker's own canonical number, use the broker.

Reading your own number without getting fooled

You now have enough to audit any dashboard in under a minute. First, find the method label. If the broker says "time-weighted", deposits are stripped and you can fairly compare to an index. If it says "personal", "dollar-weighted" or "money-weighted" — Vanguard's and Schwab's defaults, for example — the figure reflects your timing and should be compared to your own goals, not the market. If there is no label at all, as is often the case in simpler apps, assume it is some form of net-of-deposits change and treat it with suspicion the moment you've added or withdrawn cash.

Second, check the dividend and fee treatment. If your holdings pay meaningful dividends and the figure looks low, you may be reading a price return. Third, check the window: a "since inception" number on an account you opened at a lucky moment tells you little about the last twelve months. When you hold several brokers, the honest move is to put every account on the same method — the same TWR window, the same dividend treatment — before you compare or aggregate. Do that and the "my broker says one thing, hers says another" mystery dissolves entirely. For the bigger picture on tracking multiple brokers cleanly, see our guide to tracking a portfolio across multiple brokers, and the individual method notes on our broker guides.

StackViewer's role here is narrow and specific: it connects your brokers read-only, recomputes every account on one consistent time-weighted basis so the numbers are actually comparable, and shows the money-weighted view alongside when you want to know what your timing did to you. It is not trying to replace your broker's canonical statement — it exists so that a person with an ISA at one broker and a taxable account at another can finally see a single, honest, method-consistent number.

What this doesn't tell you

This is a methodology explainer, not a live audit of your account. A few limits to be square about. The broker descriptions above are each broker's documented default as of 2026-09-10 — brokers revise methodology and relabel figures without notice, so confirm against the linked help page for your own account before acting on any comparison. StackViewer itself is not real-time: it syncs three times daily and refreshes values roughly every 30 minutes, so it is unsuitable for day traders or anyone needing to-the-second figures. It connects via read-only OAuth to 31 brokers through SnapTrade; if your broker isn't on that list, or you hold custom or private assets, we can't reconcile those. Coverage of some EU brokers is thinner than US brokers, and reconnection is occasionally required when a broker rotates its OAuth tokens. Finally, nothing here — and nothing in the product — predicts future returns or constitutes advice.

Frequently asked

Why is my return different on two brokers when I made the same trades?

Because each broker uses a different formula and different assumptions. Some show a simple gain (market value minus cost basis) that ignores the timing of your deposits, some show a money-weighted rate of return that is skewed by when you added cash, and some show a time-weighted return that strips deposits out. Two brokers can display very different percentages for portfolios that behaved identically.

Which return figure should I trust to compare against an index?

Time-weighted return (TWR) is the fair figure for comparing yourself to a benchmark like the S&P 500, because it removes the distorting effect of deposits and withdrawals. Money-weighted return (IRR) tells you what you personally earned given your cash-flow timing. They answer different questions, so check which one your broker is actually showing before you draw a conclusion.

This article is for information only. It is not financial, investment or tax advice, and nothing here is a recommendation to buy or sell any security. StackViewer analyses decisions you have already made; it does not predict returns. Past performance does not indicate future results.