What a price change is measured against: different baselines for stocks, crypto and overseas markets

A price change on screen is a percentage that says how far the current value has moved above or below some baseline. One thing quietly drops out of that sentence: the point in time at which the baseline was taken.

Many people read a price change loosely as the move “over today.” But the assets Jupick covers are varied, including stocks, crypto, overseas shares, commodities and exchange rates, and each one sets its baseline at a different point in time.

So the same +1.2% can be measured against different things depending on the asset. Once these baselines are clear, most of the cases where Jupick's figures seem to disagree with another site's are explained.

For stocks listed in Korea, the price change uses the previous trading day's close as its baseline. It measures how far today's price has moved from yesterday's closing price.

While the market is open, the baseline stays fixed and only the current price moves, so the price change shows in real time where the current quote stands against the previous close. When the market closes, the figure settles at that day's close, and on the next trading day that close becomes the new baseline.

On weekends and public holidays there is no trading, so the baseline stays where it is. A “day” for Korean stocks is therefore a trading day, not a calendar day, which is worth keeping in mind.

For US and other overseas stocks, the baseline is also the previous trading day's close, and the calculation itself is the same as for Korean stocks. What differs is when, in Korean time, that trading day ended.

The US regular session opens late at night Korean time and closes in the early morning of the next day. So “today's price change” for a US stock seen during the day in Korea is often the result of a session that ended overnight. In effect there is a gap of roughly half a day between the date on the screen and the moment the value was actually set.

Jupick's asset class correlation table deals with the same limit. When assets that trade in different time zones are paired by their closing prices on the same date, a lag of about half a day is mixed in. A single price change figure carries the same lag.

The price change for crypto uses a fundamentally different baseline from the assets above. It is not the previous close but a rolling rate of change against the value exactly 24 hours before the moment of viewing.

The crypto market has no closing bell and trades around the clock. There is no “yesterday's close,” so the baseline is one day before now instead. Viewed at 3 p.m., the figure is compared with 3 p.m. yesterday; viewed at 11 p.m., with 11 p.m. yesterday.

Because of this, the crypto price change shifts with the mere passage of time, since the 24-hour window keeps sliding forward. That makes it a different kind of figure from Korean stocks, where the baseline stays fixed for the whole day.

For commodities such as gold and crude oil, and for the KRW/USD exchange rate (won per dollar), the price change uses the previous trading day's close as its baseline, the same way as for Korean stocks.

Many of these, however, trade in overseas markets, so depending on when that trading day ended in Korean time, a lag similar to the one for overseas stocks can be mixed in. The type of baseline is the same, the previous close, but the actual moment that “previous day” points to can differ from asset to asset.

Separately from these daily price changes, Jupick also calculates and shows changes over longer spans for some assets, such as the past week, the past month and since the start of the year. Even for the same asset, whether it is up or down can depend on which baseline it is compared with.

Sometimes Jupick's price change appears to differ from another site's. In most cases this is not because a value is wrong but because the baseline was taken at a different moment.

Some services cut crypto at midnight and show a daily figure; others show a 24-hour rolling figure. The way US stocks are grouped under Korean dates also varies slightly between services. Even when two screens show the same asset at the same moment, different baselines produce different numbers.

So when comparing price changes, it is better to first line up “what each value is compared against” before looking at the values themselves. Only with the same baseline can two numbers be compared as meaning the same thing.

A price change is a record of a period that has already passed. It only summarizes what happened between the baseline and the current value, and it holds nothing about what the next period brings.

A large price change does not make an asset good, and a small one does not make it bad. A price change is not a score that ranks assets; it is only the distance between two points in time.

This content is for information only and is not investment advice. Jupick does not forecast the future direction of prices and does not encourage any trade. Investment decisions and responsibility for them rest with the user.