Answer: breadth of the portfolio.

According to the fundamental law of active management: IR = IC × √BR × TC - **Breadth (BR)**: An increase in breadth increases √BR, which directly increases the information ratio, all else equal. - **Active Risk**: Active risk appears in the calculation of expected active return (IR × Active Risk), but not in the IR formula itself. Increasing active risk doesn't increase IR. - **Binding Constraints**: Constraints reduce the transfer coefficient (TC), which decreases the information ratio. Therefore, the ex-ante information ratio will most likely increase with an increase in breadth.

Author: LeetQuiz Editorial Team