Trailing Twelve Months.
A time period used in evaluating performance over time with respect to some variable relating to a defined unit - institution, government, country, customs union, company, body, brand, product, club, tax collector, outlet, salesman, etc.
For example, TTM unit sales or sales revenue or profit measure or profitability ratio, or TTM income tax collected or spending by a government or tax office, TTM seizures of contraband by custom's authorities or the TTM average number of seizures per customs officer, or TTM new members of the Association of Corporate Treasurers.
Many bodies report annual figures only annually. TTM performance measures, however, can be calculated each time the relevant figures are available. For investors in a firm, it will be when the firm reports - often quarterly or half-yearly. For insiders in a firm, commonly monthly accounts are produced, but some matters - unit sales, injury-causing accidents, for example - will be reported on more frequently.
As well as use in performance evaluation, TTM figures can also be useful in detecting irregularities such as fraud, false accounting, etc.
TTM figures are sometimes referred to as "moving annual" or "rolling annual" figures and may, for example, be expressed as "moving annual total" (abbreviated to MAT).