  Given a sufficiently symmetric domain $\Omega\Subset\mathbb{R}^2$, for any
$k\in \mathbb{N}\setminus \{0\}$ and $\beta>4\pi k$ we construct blowing-up
solutions $(u_\varepsilon)\subset H^1_0(\Omega)$ to the Moser-Trudinger
equation such that as $\varepsilon\downarrow 0$, we have $\|\nabla
u_\varepsilon\|_{L^2}^2\to \beta$, $u_\varepsilon \rightharpoonup u_0$ in
$H^1_0$ where $u_0$ is a sign-changing solution of the Moser-Trudinger equation
and $u_\varepsilon$ develops $k$ positive spherical bubbles, all concentrating
at $0\in \Omega$. These $3$ features (lack of quantization, non-zero weak limit
and bubble clustering) stand in sharp contrast to the positive case
($u_\varepsilon>0$) studied by the second author and Druet (J. Eur. Math. Soc.
(JEMS) 22 (2020)).
