Base Periods for Calculating Returns

Daily Data is usually available for stocks or mutual funds. Stock data is available in five columns: Open, High, Low, Close, and Adjusted Close at Yahoo Finance. Mutual fund data is available for daily close and adjusted daily close.

Weekly data is available on the first trading date of the week. Monthly Data is available on the first trading date of each month.

Daily Return is calculated based on the daily data.

Weekly Return has two ways. One is based on consecutive 5 trading days. This is used to calculate long-term time series (several years). Another one is based on the calendar week from Monday through Friday. This is used to calculate short-term time series (usually less than one year).

Monthly Return is calculated for each Calendar month, such as January, February, etc.

Quarterly Return is calculated for each Calendar quarter, such as 1st Quarter, 2nd Quarter, etc.

Annual Return is based on the Calendar year, such as 2001, 2002, 2003, etc.

YTD (year-to-date) return is calculated as the total return up to the current date of concern. The rate is not annualized usually.