Many altcoins rose 10-20%. My thoughts were that people bought BTC to get Bitcoin cash and now they're buying other coins. The reason this shift to altcoins hasn't resulted in a big drop in BTC is because outside/casual investors have bought bitcoin now they've seen the hardfork was a storm in a teacup. Just my theory.
I feel that the fact that this Hardfork went smoothly instilled higher casual confidence into the Market. Less technological investors will be staying with the ship.