Growth over the month and over the year: how not to get confused in market news

The same statistics can show different directions with different comparison bases.

Two bases

Monthly change compares neighboring months, annual change compares the same month of different years. They don't have to match. After a sharp drop, even a noticeable recovery may leave the indicator below the level of a year ago.

Conditional numbers

Imagine a price of 100 last September, 80 in August and 84 this September. Over the month the growth is 5%, over the year the decline is 16%. This is a shorthand for explaining arithmetic, not a message about a specific market.

Header check

Specify the period, unit and original basis. If a publication only gives percentages without these details, the conclusion is incomplete. To understand the direction, it is useful to look at the sequence of several periods and not pass off a single successful month as a stable trend.