Matrix equation align - letters and matrices

Question

I am trying to align a matrix equation so that the alignment it with the top of the column matrix A (not the centre as it is at the moment). Any help would be appreciated. Here is what I have at the moment:

\begin{document}
\begin{pmatrix}  && A^T &&  \end{pmatrix}  \textbf{B} \begin{pmatrix} \\ A \\ \\ \end{pmatrix} \begin{pmatrix}  \\ C \\ \\ \end{pmatrix} =  \begin{pmatrix}  && A^T &&  \end{pmatrix} \textbf{B} \begin{pmatrix} \\ y \\ \\ \end{pmatrix
\end{document}

Answer 1

You can construct a stackable matrix to insert your A^T in the top row so it aligns vertically with the top row of B:

\documentclass{article}
\usepackage{amsmath,bm}

\begin{document}
\[
  \bm{A}^T \bm{B} =
  \begin{array}{@{}c@{}}
    (\begin{array}{c}
      \quad \bm{A} \quad
    \end{array}) \\ \mathstrut \\ \mathstrut
  \end{array}
  \left(
  \begin{array}{c}
    \mathstrut \\ \bm{B} \\ \mathstrut
  \end{array}\right)
\]

\end{document}

The use of \mathstrut is not all that necessary here.

I prefer the regular notation, to the left of the equal sign.