https://motherboard.vice.com/en_us/article/7xyg9d/astronomers-discover-a-supermassive-black-hole-rotating-at-half-the-speed-of-light

NASA astronomers have observed a supermassive black hole that is rotating at least 380 million miles per hour, or at half the speed of light.

To put that in perspective, that means the black hole—with a diameter 300 times larger than Earth—completes a rotation roughly every two minutes.