Modelling of return and volatility as well as their dynamic spillovers between different financial markets at aggregated and disaggregated level has gained increasing interest among Financial economists. Alternative univariate and multivariate specifications have been exploited by empirical researchers to measure returns and volatility and their spillovers. However, financial markets are responsive to some specific events that have distorting effect on the model estimates. These unexpected events are depicted as outliers in the data. The estimates of GARCH type models are sensitive to the presence of outliers (Carnero et al., 2016; Charles, 2008; Charles and Darné, 2014). Studying the distortionary effects of outliers is important for the policy makers, hedge fund managers as well as investors. However, it is hard to find any study which investigates the impact of outliers and spillovers keeping in view the sensitivity of GARCH type models to the outliers in context of Pakistan Stock Exchange (hereafter PSX). This study firstly examines the effect of outliers on the returns, volatility and their dynamic spillovers between Pakistan Stock Exchange and world selected stock markets., Secondly, among different sectors of Pakistan Stock Exchange and thirdly, between sectors of Pakistan Stock Exchange and Brent oil market. Finally, the optimal portfolio weights and hedge ratios for both outliers contaminated returns and outliers adjusted returns are calculated. This study employs the Laurent et al. (2016) method and the Charles and Darné (2005) methods for the detection and correction of outliers. To quantify the dynamics of returns, volatility and their spillovers for unadjusted and adjusted returns, the model of Ling and McAleer (2003) and McAleer et al. (2009) are estimated. Furthermore, daily data sampled from January 01, 2001 to December 31, 2015 was retrieved from DataStream for estimation. II The results of the study at market level indicate that the estimates of conditional mean and conditional variance of Pakistan Stock Exchange are insensitive to the choice of foreign stock market. Furthermore, these coefficients did not change with the correction or non-correction of outliers except intercept of volatility equation. The presence of outliers results in overestimation of intercept term in volatility equation of Pakistan Stock Exchange in all pairs with selected stock markets. The developed stock markets and Indian stock market have significant return spillovers effect to Pakistan Stock Exchange; however, they were slightly overvalued due to the presence of outliers in the data.It was evident that the markets shocks of the US and Euro region spillovers to Pakistan Stock Exchange. In contrast, shocks and volatility of Pakistan Stock Exchange spillovers to Indian stock market only for both unadjusted and adjusted returns. Outliers adjusted returns reduced these spillovers marginally. Presence of outliers did not show significant effect on the estimated values of optimal portfolio weights and hedge ratios. Sectoral analysis of Pakistan Stock Exchange leads to the conclusion that first and second conditional moments of a sector were sensitive to the choice of other sector in the pair. The outliers’ adjustment has sensitivity reducing effect on conditional mean and variance of sectoral returns. The intercept terms in all sectoral stock return volatility equations were well above its market counterpart. Moreover, the estimates of GARCH coefficients revolve around market volatility estimates. Although return spillovers have been observed in some of the sectors but overall the return spillovers are insignificant for both unadjusted and adjusted returns. In contrast to the market level, short run and long run volatility spillovers are sensitive to the presence of outliers. The results also showed that adjustment of outliers have significant impact on the estimates of optimal portfolio weights and hedge ratio. III Finally, we study the effect of outliers on the returns and volatility as well as their spillovers between Brent oil and Pakistan Stock Exchange. The analysis revealed that mean and volatility estimates of Pakistan Stock Exchange bench mark index returns, and oil market returns are non-responsive to presence of outliers. Short run price spillover is found significant from oil market to Pakistan stock market both at market and sectoral levels. Whereas, no transmission of short run as well as long run volatility exist between these two markets for both unadjusted and adjusted returns. The optimal portfolio weights and hedge ratios remains identical for both unadjusted and adjusted returns. The findings are worth interesting for the investors and policy makers.