as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
what time period is used by yahoo finance to calculate beta
user
citing the yahoo finance help page, beta: the beta used is beta of equity. beta is the monthly price   change of a particular company relative to the monthly price change of   the s&p500. the time period for beta is 3 years (36 months) when   available. regarding customised time periods, i do not think so.
assistant