Left margin minipage two figures

You can use a box and trick latex to think that the box has zero width and then center it:

\documentclass{article}
\usepackage{graphicx}
\usepackage{showframe} %% just to show frames.

\begin{document}

\begin{figure}[htb]
\centering
\makebox[0pt][c]{%
\begin{minipage}[b]{0.6\linewidth}
\centering
  \includegraphics[scale=0.4]{example-image-a}
  \caption[VaR assuming normal distribution, Allianz]{VaR assuming normal distribution, Allianz}
\label{sva}
\end{minipage}%
\hspace{0.5cm}
\begin{minipage}[b]{0.6\linewidth}
\centering
 \includegraphics[scale=0.4]{example-image-b}
  \caption[VaR assuming normal distribution, Basf]{VaR assuming normal distribution, BASF}
\label{svb}
\end{minipage}%
}%
\end{figure}
\end{document}

This can also be done with adjustbox package.

A \hspace{} is enough to do the trick. Add this in front of the first minipage (how much space depends on the particular case).

\documentclass{article}
\usepackage{graphicx}
\usepackage{showframe}

\begin{document}

\begin{figure}[htb]
\hspace{-1.6cm}\begin{minipage}[b]{0.6\linewidth} %%% ADDED HERE %%%
\centering
  \centerline{\includegraphics[scale=0.4]{example-image-a}}
  \caption[VaR assuming normal distribution, Allianz]{VaR assuming normal distribution, Allianz}
\label{sva}
\end{minipage}
\hspace{0.5cm}
\begin{minipage}[b]{0.6\linewidth}
\centering
 \centerline{ \includegraphics[scale=0.4]{example-image-b}}
  \caption[VaR assuming normal distribution, Basf]{VaR assuming normal distribution, BASF}
\label{svb}
\end{minipage}
\end{figure}

\end{document}