Backward-adjusted prices
On an ex-dividend date a share price drops by roughly the amount being paid out. That fall is not the market repricing the company — it is cash leaving the share and landing in the holder's account. A return computed on raw prices records it as a loss anyway. This page returns the backward-adjusted series next to the raw close, with the adjustment factor for every day, so the correction is visible rather than assumed.
- A high-yield name can drop several percent in one session with nothing having happened, which is enough to fire a stop in a backtest.
- Moving averages, momentum and range indicators all break across an ex-date if the level shifts underneath them.
- Maintaining your own factor table from dividend filings is reconcilable work you have to redo every season.
Try it
Enter a ticker — the free key covers the demo ticker 2330. Candles are the adjusted series, the grey line is the raw close. Where the two separate, that gap is the dividends paid since. The cells underneath put a number on it.
How it is built
Four steps, all of them arithmetic you can redo from the API response. There is no model here and nothing to tune.
Read the official corporate action filings
Cash dividends, stock dividends and rights issues come from the official ex-dividend and ex-rights calculation notices, reproduced as published rather than taken from a third-party feed. If the exchange says the reference price moved by a given amount on a given date, that is the number used.
Compute one adjustment factor per ex-date
Each ex-date gets a single ratio that expresses how much of the price drop was the dividend leaving rather than the market moving. Nothing is estimated or smoothed here; the factor falls straight out of the filing.
Multiply the factors backwards through history
The factors are chained backwards from today, so the most recent close is left untouched and every earlier price is scaled down by the dividends that have been paid since. The last adjusted close on the chart is therefore always identical to the last raw close — that identity is the easiest way to check the series is backward-adjusted rather than forward-adjusted.
Scale open, high and low by the same day's factor
The three other price points on a bar use the factor for that day, so the candle keeps its shape and only its level changes. Any indicator that reads highs and lows — ranges, breakouts, stops — stays internally consistent.
Terms
Four words carry most of this page:
Where the line is
Backward adjustment is the right default for measuring returns and the wrong one for asking what a price was on a given day. The adjusted close for a date three years ago is not what anybody paid then — it is that price expressed in today's post-dividend terms. Anything that depends on the actual traded level, such as reconstructing a limit order or checking a tick size, needs the raw close, which is why both are returned on every row rather than one replacing the other.
The series also changes after every future ex-date, since the whole history is rescaled again. That is a property of backward adjustment, not a defect, but it does mean an adjusted price is not a point-in-time value: it is derived from corporate actions that had not happened yet on the date it describes. The adjustment factor is therefore returned in the open rather than folded silently into the price, so any study that needs the as-of level can undo the adjustment exactly.
FAQ
Why can't I just use the raw closing price?
Because a return computed across an ex-date on raw prices treats the dividend as a loss. On a high-yield Taiwan name that is several percent in a single session, which is enough to trigger a stop in a backtest, break a moving-average crossover, and understate the holding period return by the entire dividend stream. The error is not random noise — it is a systematic drag that grows with yield, so it hits exactly the strategies that hold dividend payers.
Is this forward-adjusted or backward-adjusted?
Backward-adjusted. The most recent adjusted close equals the most recent raw close, and earlier prices are scaled down. That means the chart agrees with what you would see on a quote screen today, and it also means the series changes shape after every future ex-date — which is why the adjustment factor is returned alongside the price rather than hidden inside it.
Where do the corporate actions come from?
From the official ex-dividend and ex-rights calculation notices, reproduced as published. Cash dividends, stock dividends and rights issues are all handled; the factor for each ex-date is derived from the filed figures rather than inferred from the price move.
Can I recompute the adjusted series myself?
Yes, and that is the point. The response carries close, adj_close and adj_factor for every row, so adj_close ÷ close reproduces the factor and multiplying any raw price by it reproduces the adjusted price. Nothing on this page is a black box you have to take on trust.
Is it free?
The demo ticker 2330 is open on the free tier with no signup. Adjusted series for any ticker is a paid-tier feature, available from the same API endpoint shown above the chart.
Run it yourself
The free tier needs no signup — call this feature's API straight away with the demo key. Unlock as-of history and full ticker coverage on a paid tier.