TTM and YoY are two shorthands you meet in fundamental filters and in the Unit line under a results column header. TTM (trailing twelve months) sums the last four reported quarters into a rolling one-year figure that always ends at the most recent report, rather than at a fiscal year-end. YoY (year over year) compares a figure to the same figure one year earlier, showing the change over a full year and cancelling out seasonal ups and downs.
Also seen as: LTM
How is a year-over-year change calculated?
A year-over-year change is the difference between the current figure and the figure one year earlier, divided by that earlier figure.
where: is the current value and is the value one year earlier.
Why TTM and YoY are used
TTM gives an up-to-date annual figure between fiscal year-ends: instead of waiting for the full-year accounts, it adds the four most recent quarters, so the number moves every reporting season. YoY strips out seasonality: comparing this quarter to the same quarter last year avoids the distortion of holding a holiday quarter against a summer one.
What does it look like in practice?
Suppose a company's fiscal year ends in December. After it reports Q3, its fiscal-year revenue still shows last December's full-year total — up to nine months stale. Its TTM revenue instead sums Q4 of last year plus Q1, Q2, and Q3 of this year, giving a rolling twelve-month total that already reflects the most recent quarter. If that TTM figure is 8% above the TTM a year earlier, its revenue YoY is +8%.