What does 'Trailing' mean
Trailing is the most recent time period, often used to describe the time that a particular set of data is referring to. Trailing is used to describe a past statistic, such as same-store sales, but can also be used to describe a technique, such as a trailing stop order. Most often you will hear the term "trailing 12 months," "trailing three months" or "trailing six months."
BREAKING DOWN 'Trailing'
The term may also modify a reported metric. For example, the earnings in a trailing price-to-earnings ratio refers to the past earnings per share over a certain period - usually 12 months. Trailing 12 months is denoted by the acronym "TTM."