% use "latex" to generate a *.dvi file, and use "dvisvgm --no-fonts" to convert to .svg
\documentclass[tikz, border=5mm]{standalone}
\begin{document}
\begin{tikzpicture}[scale=0.5]
  \draw[fill=black!5] (0,0) rectangle node {$A$} +(3,7);
  \node at (3.5,3.5) {=};
  \draw[fill=black!5] (4,0) rectangle node {$U_n$} +(3,7);
  \draw (7.25,4) rectangle +(3,3) (7.25,7) -- +(3,-3);
  \node[below] at (8.75,4) {$\Sigma_n$};
  \draw[fill=black!5] (10.5,4) rectangle node {$V_n^*$} +(3,3);
\end{tikzpicture}
\end{document}
