\begin{table}[H]\centering\small
\caption{AI~disclosure $\times$ size double sort: mean forward 12-month return (\%). Within each size half, firms are split into AI terciles.}\label{tab:doublesort}
\begin{tabular}{lcccc}\toprule
& Low AI & Mid AI & High AI & Hi$-$Lo \\\midrule
\multicolumn{5}{l}{\textit{Panel A. Pre-ChatGPT (2010--2021)}}\\
Small & 19.7 & 21.9 & 23.6 & +3.9 \\
Large & 13.8 & 14.3 & 13.6 & -0.1 \\
\midrule
\multicolumn{5}{l}{\textit{Panel B. Post-ChatGPT (2022--2024)}}\\
Small & 19.5 & 19.2 & 34.5 & +15.1 \\
Large & 15.8 & 18.3 & 22.9 & +7.1 \\
\bottomrule
\end{tabular}\end{table}