\begin{table}[H]\centering\small
\caption{Difference-in-differences around ChatGPT. Dependent variable is the winsorized forward 12-month return; firm and year fixed effects; SE double-clustered by firm and year. Treatment is fixed at the firm's pre-event (2019--2021) AI exposure.}\label{tab:did}
\begin{tabular}{lcc}\toprule
& Treated$\times$Post & Exposure$\times$Post \\
& (binary) & (continuous, per SD) \\\midrule
Coefficient & 0.0170 & 0.0269 \\
\textit{t}-statistic & (0.78) & (1.51) \\
N (firm-years) & 6790 & 6790 \\
Firm \& Year FE & Yes & Yes \\\bottomrule
\end{tabular}\end{table}