Dividend Adjustment (qfq / hfq)

TL;DR: For getHistoryKline / getMinuteKline / getHKHistoryKline / getUSHistoryKline, the adjust parameter defaults to 'qfq' (forward-adjusted / front-adjusted). If you are running back-tests or computing dividend-reinvested returns, always pass 'hfq' or '' explicitly.

Three adjustment types

Value	Meaning	Price behavior	Typical use case
''	Unadjusted	Raw exchange-traded prices	Trade reconciliation, order-book analysis
'qfq'	Forward-adjusted (default)	Anchored to the most recent corporate action; historical prices scaled down accordingly	Charting, technical indicators, trend analysis
'hfq'	Backward-adjusted	Anchored to the IPO; dividends/splits compounded forward, prices grow over time	Total return, back-testing, compound returns

Why is 'qfq' the default?

Most financial websites and brokerage platforms display K-lines as forward-adjusted by default, so the price line has no visible gap on ex-dividend days and looks visually continuous.

But forward-adjusted "prices" are not the actual traded prices: if a stock traded at 100 before a dividend in 2020 and 50 after, today's forward-adjusted history will report ~50 for that 2020 day. You cannot use that number to back-calculate "what I actually paid back then".

Choosing per scenario

Scenario 1: Charting & technical indicators (MA / MACD / BOLL / etc.)

Use 'qfq' (default).

const klines = await sdk.getHistoryKline('sh600519');
// equivalent to:
// const klines = await sdk.getHistoryKline('sh600519', { adjust: 'qfq' });

Technical indicators are statistical transforms over price series and need a continuous, gap-free input. Forward adjustment delivers exactly that.

Scenario 2: Back-tests & long-horizon returns

Use 'hfq', explicitly.

const klines = await sdk.getHistoryKline('sh600519', { adjust: 'hfq' });
const totalReturn = (klines.at(-1)!.close! / klines[0].close! - 1) * 100;
console.log(`${totalReturn.toFixed(2)}% cumulative return`);

Under backward-adjusted prices, last-close / first-close is the true cumulative return (assuming dividends are reinvested). Forward-adjusted prices would understate the return because they strip away the dividend uplift.

Scenario 3: Trade reconciliation, historical cost lookup

Use '' (unadjusted).

const klines = await sdk.getHistoryKline('sh600519', { adjust: '' });
const dayKline = klines.find(k => k.date === '2020-06-24');
// dayKline.close is the actual close price as printed on that trading day

Only unadjusted prices match what your broker statement / historical position cost shows.

HK / US

getHKHistoryKline / getUSHistoryKline also default to adjust: 'qfq'. The selection logic is identical to A-shares.

1-minute timeline does not support adjustment

getMinuteKline(symbol) (period='1' default) hits EastMoney's trends2/get endpoint which does not accept an adjustment parameter. The 5/15/30/60-minute K-lines hit kline/get and accept adjust='qfq'/'hfq'/'' like the daily K-line.

Common pitfalls

Never compute cumulative return from forward-adjusted data

// ❌ Wrong
const klines = await sdk.getHistoryKline('sh600519'); // default qfq
const totalReturn = klines.at(-1)!.close! / klines[0].close! - 1;
// This excludes dividend yield and may understate the true return by 20-50%.

Never use forward-adjusted prices to look up historical cost basis

A forward-adjusted "historical price" has been scaled and does not equal the actual filled price. For historical cost, use adjust: ''.

Different adjust values return different OHLCV

This is not a bug — it is how price adjustment works. Pin the value you need explicitly so your downstream calculations stay reproducible.