Equity Curve: Why It Is Read by Its Shape, Not Its End Point

An equity curve is the line of an account's or trading system's accumulated capital over time: the horizontal axis shows time, and the vertical axis shows the portfolio's value on each date. What matters is not where it ended, but the path it took to get there. Two curves with the same final value can describe entirely different strategies: one climbed in steps with shallow pullbacks, while the other collapsed almost to its starting level and recovered only in the final stretch. For trading purposes these are different instruments, and only the shape tells them apart.

What exactly goes on the vertical axis

The first thing to establish is which quantity counts as equity. Two approaches are common, and they produce different lines.

Closed-trade equity counts only completed trades: capital changes at the moment a result is booked. The line comes out stepped and tidy, but it hides everything that happened while a position was open.

Mark-to-market equity reflects the current value of open positions every day. The line becomes jagged — but honest: it shows how deep a position went underwater before it moved into profit.

The gap between these two methods is precisely the share of risk a trader lives through but never records in the trading journal. If a system holds positions for a long time, mark-to-market is the version to look at.

Drawdown: the key measure read from the curve

A drawdown is the decline in equity from a peak to a subsequent trough. It is read from the curve along several dimensions at once: depth (how far capital fell), duration (how long the line spent below its previous high) and the time taken to recover to a new peak.

Duration often matters more than depth. A short, sharp drop is easier to endure than a sluggish plateau that drags on for months: it is on the plateau that a strategy is usually abandoned — not because it has stopped working, but because patience runs out before the statistics have a chance to show through. That is why a curve's shape should be judged not only by its worst point but also by the share of time the line spent in drawdown.

The source of growth deserves a separate look. If the curve's rise rests on a handful of lucky trades while the bulk of results is negative, the curve describes not a system but chance, which the sample cannot distinguish from skill.

What the equity curve does not show

The capital line is silent on a great deal, and this is its main limitation.

• Number of trades and sample size. A curve looks equally convincing with a few dozen trades and with several thousand, yet the statistical significance differs dramatically.
• Executability. Slippage, the spread, commissions and liquidity enter a backtest curve only if they were built into it. For illiquid securities from the list of stocks, the gap between the modelled and the actual curve can be decisive.
• Market regime. A curve built over a period containing a single uptrend describes that trend, not the strategy.
• Dividends and coupons. Equity based on the price series and equity based on total return diverge more the longer the period. Upcoming payments —; for the full schedule, see the dividend calendar.
• Event backdrop. Gaps in the curve almost always have an identifiable cause: an earnings release, a rate decision, a corporate action. Check the kinks against the events calendar and the news feed — otherwise you risk crediting the strategy with what the market did on its behalf.

Not to be confused with the yield curve

The similar names are misleading. The equity curve is capital as a function of time for a specific account. The yield curve is yield as a function of time to maturity, a snapshot of market expectations on a given date, and it has nothing to do with an individual trader's results. How to read its shape is covered in our piece on the OFZ yield curve; other related concepts — the zero-coupon yield curve and the swap curve — are also about maturities, not capital. Definitions are collected in the glossary.

Comparing against a benchmark

The absolute shape of a curve means little without a basis for comparison. An equity strategy is measured against the capital curve of money invested in the index or in the stock itself: the SBER profile provides a starting point for such a check. A bond strategy is compared with holding the issue to maturity — the source data are in the bonds section and, separately, under OFZ.

A useful technique is to plot not the equity itself but its ratio to the benchmark. Such a line rises only when the strategy outperforms passive holding, and it instantly strips out the effect of a broad market rally. Many curves that look convincing on their own turn into a flat band once expressed in relative terms.

Review checklist

Step 1 — make sure equity is calculated on a mark-to-market basis, not just from closed trades. Step 2 — write down the depth, duration and recovery time of the worst drawdown. Step 3 — check whether the entire result rests on a handful of trades. Step 4 — plot the ratio to the benchmark. Step 5 — match the kinks against real events and financial statements from the reports section.

The equity curve is a diagnostic tool, not an argument. It is good at showing how a system behaves in bad periods, and poor at showing whether a good period will repeat.