It’s from the beginning of their most recent usual reporting period until today.
If a company has a fiscal year that corresponds to a calendar year, for example, and issues an interim report on April 10, then period-to-date returns would be from January 1 to April 10. It simply means “returns so far this period”.
say you received a 10% one month return - would you say you achieved an annualized return of 120% (assuming arithmetic)- aren’t you overstating / mistating the performance - and thus “inflating” expectations?
I assume you mean “why you cannot annualize returns when the holding period is less than one year”. Because then you’re not reporting your performance; you’re reporting an extrapolation of your performance. You’re merely guessing about what you would have done for the rest of the year. In a performance report you’re not allowed to guess.