So it&#x27;s not explicitly ruled out by relativity. However, that link says:<p>&gt; The Universe at large appears to be electrically neutral, or close to it. Thus real black holes are unlikely to be charged. If a black hole did somehow become charged, it would quickly neutralize itself by accreting charge of the opposite sign.<p>&gt; It is not clear how a gravitationally repulsive, negative-mass singularity could form.<p>So it falls under the same sort of category as negative- or imaginary-mass &#x27;exotic matter&#x27;: not ruled out, but there&#x27;s nothing suggesting that it actually exists.