\begin{table}[H]\centering\small
\caption{ChatGPT event study (event date 30 Nov 2022; market-model abnormal returns estimated over Jan--Oct 2022). Mean cumulative abnormal return (CAR, \%) by pre-event AI-disclosure tercile (from the FY2021 10-K), and the High$-$Low difference with a Welch \textit{t}-test.}\label{tab:event}
\begin{tabular}{lrrrrrr}\toprule
Horizon & High & Mid & Low & High$-$Low & \textit{t} & \textit{p} \\\midrule
+60 trading days & +1.89 & +1.79 & -1.04 & +2.93 & 1.77 & 0.077 \\
+6 months & -2.72 & -5.17 & -7.25 & +4.53 & 1.60 & 0.110 \\
+1 year & -6.38 & -11.80 & -16.46 & +10.08 & 1.97 & 0.050 \\
+18 months & -8.46 & -16.03 & -23.05 & +14.59 & 1.89 & 0.060 \\
\midrule
\multicolumn{7}{l}{\footnotesize Cross-sectional regression, CAR(+1y) on pre-event AI exposure (per SD):}\\
\multicolumn{7}{l}{\footnotesize\quad No sector FE: $+3.13$\% \tstat{1.39}, $n=483$, $R^2=0.160$ \quad
With sector FE: $+2.09$\% \tstat{0.99}}\\
\bottomrule
\end{tabular}\end{table}