TSX Market Making Program Guide Responsibilities of Market Makers TMX Group Page 16 In special circumstances such as extreme market volatility or where systems issues interfere with the ability of a Market Maker to reasonably meet its obligations, TSX may use its discretion to adjust performance obligations, either for a particular security or on a market wide basis. 3.2.2 Measurement of Each Market Maker’s Contribution to Stock Level Performance Obligations Each of the two MMs assigned to a security receives a Contribution Score which measures their contributions relative to each other in maintaining the symbol level performance targets. The Contribution Score is based on each MM’s contribution to achieving each of the Spread Goal (“SG”), %Time at NBBO, and Top of Book (“TOB”) Size symbol level performance targets. Spread Goal and % Time at NBBO contributions are assessed in terms of a net corrections component and a % time alone at target, called Alone Presence component, while TOB size contributions are assessed in terms of each MM’s overall average contribution to the TOB size where not fulfilled by natural liquidity, called TOB Size Contribution. The final overall Contribution Score is calculated by combining the MM’s score in each of the three measured categories. Each of the three categories is given even weighting in calculating the final Contribution Score. The breakdown of the three categories is as follows: SG measurements = 33.33% o Relative Net SG corrections = 50% total SG weight o Relative SG Alone Presence = 50% total SG weight % Time at NBBO measurements = 33.33% o Relative Net NBBO corrections = 50% total NBBO weight o Relative NBBO Alone Presence = 50% NBBO weight TOB size measurements = 33.33% The measurements are detailed in Table 2 – Single Market Maker Measurement.