People don't understand the market. The value went up to a nice spot so people started selling their stocks which lowers the price. People buy it, let it sit a bit and it goes up. Process repeats. It's a roller coaster. With Obama, it was a roller coaster at sea level. With Trump it's a roller coaster on the side of a mountain.
Expect up and downs around those levels for the remainder of his term. If he pulls another trick, the coaster will move up the mountain but it's still going to go up and down. If he does nothing, the coaster will start to slide down the mountain because that's just how things work.