Texas-based utility stock Vistra Corp (NYSE:VST) is slipping today, down 5.7% at $205.49 at last glance, after suffering a downgrade from Jefferies to "hold" from "buy." The firm also slashed its price target to$230 from $241, following the stock's meteoric rise “beyond what any bull could have predicted years ago.”VST hit a record high of$219.73 just last session, a large jump from the $30 level it was trading around two years ago. The stock's most recent climb pushed it above a coalition of short-term m ...