Stock Themes

How stock themes are built and what the numbers mean

A theme is a group of companies that share a business, a supply chain or a customer, put together by hand rather than by sector classification. A steel mill and a magnet producer sit in the same official sector and have nothing else in common; a chip designer and a company making the optical links between its processors sit in different sectors and rise and fall together. Themes follow the second logic.

Each group is rebuilt every night from closing prices, and four numbers appear on every card.

The change is the average move of every stock in the group over the last five trading days, and it is what the page is sorted by, strongest first. Five trading days rather than a calendar week, so a weekend or a holiday stretches the period over more days than five. The count beside it says how many members rose over that same span: seven out of seven means the whole group moved, while four out of ten means one or two names carried the average and the rest did not follow. That distinction is the reason it is shown as a fraction rather than a percentage.

The leader is the strongest member of the group over those five days, and the top mover is whichever member has risen most so far today. The percentage beside both is today's change, live, so a leader can be red while still being the name that pulled the group up over the five days.

None of this is a recommendation. A group moving together says something about where money is going; it says nothing about whether any individual name is worth owning.