FY1 means the current forecast year, so if we are in March, it would usually be the year ended next December.

It does, however, depend when the company's year-end is (whereas this is not the case with a rolling ratio).

Research has shown that analysts forecasts have a tendency to trend.

Analysts often get 'anchored' to their previous forecasts and only ratchet forecasts up or down cautiously in reaction to new events.