This is CNBC's Morning Squawk newsletter. Subscribe here to receive future editions in your inbox.Here are five key things investors need to know to start the trading day:1. Witching hourA trader works at his desk on the floor of the New York Stock Exchange (NYSE) after the opening bell in New York on December 3, 2025. Timothy A. Clary | Afp | Getty ImagesWall Street could be in for a wild trading day when options on four types of securities expire: index options, single stock options, index futures and ind ...