Ulusoy, VeyselEken, M. HasanCankaya, Serkan2024-03-132024-03-1320111993-8233https://hdl.handle.net/20.500.12662/4095This study investigates intraday effects in the Istanbul Stock Exchange (ISE) during the latest period of financial turmoil which began in August 2007 and extended to February 2010. We tested for the possible existence of intraday anomalies using both return and volatility equations, empirically applying GARCH (p,q) models. The unique data set we utilized was compiled from 15-min intraday values of the ISE-100 Index which are formed by averaging historical ten-second tick data. This study contributes to the current literature in three distinct ways. Firstly, the basic characteristics of the unique data used in this research were investigated in detail. Secondly, four range-based volatility measures, namely Garman Klass (GK), Yang-Zhang (YZ), Rogers-Satchell (RS) and Parkinson (PK), were employed to take more precise measurements of volatility for intraday data analysis in order to identify the changes in general market sentiment using opening, closing, high and low prices. Thirdly, we estimated the relative efficiency of GK, YZ, RS and PK by applying GARCH (p, q) models. The results are quite promising, indicating that strong opening price jumps are present for daily and morning calculations. They illustrate that the YZ estimator has relatively more power in generating tolerable volatility patterns.eninfo:eu-repo/semantics/closedAccessIntraday volatilityGARCHIstanbul Stock ExchangeArticle70301670175WOS:000297623400037N/A