# Thirty-day move

> The 30-day column is a short-term momentum read: how a position's price has changed over the last month. Useful for spotting what moved, misleading as a signal.

The thirty-day move shows how a position's price has changed over roughly the
last month.

It is a scanning tool. Sorting the holdings table by it answers "what has
actually been happening lately", which is a different question from "what has
done well", and a much better use of thirty days of data.

## What it is not

Thirty days is a short window, and the number is best treated as a description
rather than a signal.

**It has no memory.** A position down 4% over thirty days might be down 4% from
a long climb or down 40% from a peak two months ago. The column cannot tell you
which. The instrument chart can.

**It ignores income.** The move is a price change, so a position that paid a
dividend during the window will look weaker than your actual return was. On a
high yielding holding around an ex-dividend date, this is visible.

**It is noisy.** A month of price movement is mostly noise for most assets.
Ranking a portfolio by it produces a leaderboard that reshuffles constantly and
predicts very little.

## Where it is useful

Two cases where a short window genuinely helps.

Explaining a change in your total. When the portfolio moved and you want to
know which holdings drove it, sorting by this column finds them quickly.

Spotting something you had not noticed. A position that has moved sharply while
you were not looking is worth knowing about, whichever direction it went.

For the same question over a period you choose rather than a fixed month, the
Performance tab's return drivers show which positions produced the return and
how many percentage points each contributed, across whatever window you have
selected.

## Centrally priced holdings

Anything Gylder prices daily, including securities, crypto and metals, has a
genuine thirty-day move. Manual holdings valued from figures you typed do not,
since their value only changes when you update it, and a move calculated from
your own edits would say more about when you last logged in than about the
asset.