\begin{table}[htbp]\centering\small
\caption{Main (held-out): WIS relative to Random walk (trailing RMS)}
\label{tab:main_cmp_wis_heldout}
\begin{adjustbox}{max width=\textwidth}
\begin{tabular}{lcccc}
\toprule
Model & $H=5$ & $H=15$ & $H=30$ & $H=60$ \\
\midrule
Seasonal volatility & -3.11\% (-34.4) & -3.15\% (-35.6) & -3.25\% (-29.5) & -3.48\% (-23.2) \\
EWMA-$t$ & -3.68\% (-40.4) & -3.53\% (-38.1) & -3.36\% (-27.3) & -3.19\% (-18.8) \\
HAR-RV & -3.10\% (-36.8) & -4.11\% (-47.4) & -4.19\% (-37.4) & -4.44\% (-29.8) \\
GARCH(1,1)-$t$ & -3.37\% (-37.5) & -3.25\% (-35.9) & -3.05\% (-25.8) & -2.75\% (-17.5) \\
Ridge & -3.32\% (-29.4) & -4.03\% (-41.1) & -4.25\% (-34.7) & -4.59\% (-28.6) \\
Elastic net & -3.32\% (-29.5) & -4.02\% (-41.0) & -4.24\% (-34.5) & -4.61\% (-28.7) \\
LightGBM & -2.55\% (-21.5) & -3.94\% (-39.9) & -4.11\% (-33.3) & -4.49\% (-27.6) \\
MLP (1m) & -4.18\% (-49.9) & -4.10\% (-48.2) & -4.05\% (-37.4) & -4.21\% (-28.5) \\
TCN (1m) & -4.29\% (-51.3) & -4.16\% (-50.6) & -4.09\% (-39.6) & -4.20\% (-30.7) \\
MRPT-S (1m+5m+30m) & -4.41\% (-50.8) & -4.34\% (-50.9) & -4.33\% (-40.3) & -4.59\% (-31.7) \\
MRPT-S (1m only) & -4.36\% (-50.6) & -4.28\% (-50.0) & -4.26\% (-39.6) & -4.47\% (-31.3) \\
MRPT-B (1m+5m+30m) & -4.39\% (-51.2) & -4.31\% (-50.8) & -4.30\% (-40.5) & -4.52\% (-31.7) \\
\bottomrule
\end{tabular}
\end{adjustbox}
\begin{minipage}{0.95\textwidth}\scriptsize Relative change in mean WIS versus the reference (negative = better); Diebold--Mariano $t$-statistic with HAC variance in parentheses.\end{minipage}
\end{table}