Adjustment convention

The short version

/v1/kline prices are always forward-adjusted — there is no adjust parameter and none is needed, and prices do not gap on ex-dividend dates.

What forward adjustment means

Historical prices are back-adjusted by each ex-dividend / ex-rights ratio, using the latest price as the reference point.

The benefit is a continuous price series: on the day a stock pays a dividend or splits, the chart does not drop by a sudden hole, so moving averages, patterns and percentage changes are not distorted by it.

The trade-off is that historical prices change over time — every ex-dividend event recomputes all earlier prices. The same stock’s historical K-line can therefore return different values today than it did last month. For backtesting, re-fetch the data each time rather than caching old price series for long.

Three things to know

1. There is no adjust parameter

/v1/kline accepts only code, period and count. Passing adjust will not be recognised — the convention is fixed, there is nothing to choose.

2. No gap on ex-dividend dates

Moving averages, pattern detection and technical indicators are not fooled by the ex-dividend hole. That is the direct benefit of a fixed forward adjustment.

3. Do not double-adjust

If you splice unadjusted data from another source (or data adjusted a different way) together with the prices we return, or apply another adjustment pass on top, the series is wrong — that is double adjustment.

How to check it yourself

Take a stock’s close series (last in each data row) for three days either side of an ex-dividend date and look at whether it is continuous:

• Continuous (no sudden step or hole) ⇒ the convention is working.
• A visible gap ⇒ first confirm the stock really did go ex-dividend that day (check the announcement), then investigate.

Common misuses

• Passing adjust — the parameter does not exist; the convention is fixed.
• Splicing in unadjusted data — double adjustment; the series is wrong.
• Caching historical K-lines for a long time — forward adjustment recomputes on each new ex-dividend event, so stale caches go out of date.