Index gains for the session: what the daily change measures and what it does not show

The list below shows the indices that rose over the current trading day, sorted by the size of the daily change from largest to smallest. It is recalculated every time the page is served: the constituents and the order change daily, so it should be read as a snapshot of the market on a given date, not as a verdict on where things are going better.

What exactly is measured

There is a single criterion here: the percentage change in the index value relative to the previous close. Not return, not corporate earnings, not valuation — only the difference between two points on the curve that lie closest to each other in time.

An index is a weighted basket of securities with set rules for selection and weighting. Its value changes when the prices of its constituents change, and it does so disproportionately: a security with a large weight pulls the index harder than a security with a small weight, even if the latter has risen more noticeably. That is why a daily gain in an index does not mean that most of the securities in it have risen. The exact opposite happens too: the index is in positive territory while underneath it there are mostly declines, outweighed by the move in a few heavyweight positions. This can only be checked against the constituents, not against a line in the ranking — for the Russian market, see stock quotes.

The second thing that determines the result is the methodology of the index itself. A price index counts only the change in prices, a total return index adds reinvested dividends, and a currency version converts the basket into a different monetary unit and therefore also contains the exchange rate move. Two versions of the same market can stand far apart in a table of daily changes, and both will have been calculated correctly. What each of the familiar index families actually measures is covered separately: world indices and their calculation bases.

What cannot be concluded from this criterion

The daily change is the shortest possible observation interval, and it has an awkward property: it contains almost no information about direction. An index can rise over a session while in a prolonged decline, and fall within a sustained advance. Sorting by daily change answers the question "what moved today", not "what is moving in general".

What does not follow from the list:

• That a market is "stronger" than another. That requires comparable periods, a common calculation currency and the same type of index.
• That the rise will continue. The criterion describes the session that has passed and has no forecasting component.
• That the reason for the rise is known. The size of the change does not explain itself; the reason is to be found in financial reports, the events calendar and the news flow — see the events calendar and market news.
• That an index can be followed directly. An index is a calculated value, not an instrument; access to the basket is provided by a fund with its own rules and costs, and its result differs from that of the index. The list of available instruments is in the funds section.

Why indices diverge on the same day

The divergence is created by three different mechanisms, and it is useful to tell them apart.

Composition and concentration. A narrow sector index is moved by a small group of securities, a broad index by an average across the whole market. That is why sector indices occupy the edges of the list more often: both the top and the bottom.

Technical gaps. On the day following the ex-dividend date of a large issuer, a price index loses the amount of the payout with no connection whatsoever to the state of the business. This is an accounting event, not a market move, and it is not visible in a total return index. The dates after which such gaps appear are gathered in the dividend calendar; how to use it is explained in a separate article.

Rebalancing of the base. Index providers periodically change the constituents and the weights. On the review date, the change in the index partly reflects not prices but the new basket.

How to read the list above

The order is useful as a starting point, not as a conclusion. A sensible sequence of work looks like this.

Step 1 — look at what type of index has ended up in the upper part: broad market, sector, currency version. This immediately explains most of the size of the move.

Step 2 — open up the constituents and check whether the whole basket stands behind the rise or just individual heavyweight securities.

Step 3 — compare it with a long period. A daily gain within a downward move and a daily gain on the continuation of an advance are different observations, although in this table they look the same.

Step 4 — find the event-driven cause, if there is such a cause: financial results, a rate decision, a dividend date. For the debt market, a cross-section of yields is also useful — OFZ and corporate issues react to the same decisions differently from equities, and this divergence is informative in itself.

Unfamiliar labels in the table rows — index type, calculation base, currency — are explained in the glossary.

Finally, an honest caveat about the limits of this page: it sorts indices by daily change and asserts nothing more. The intraday range, trading volumes and the reasons for the move are not part of this criterion, and they must not be inferred from the size of the gain.