Complex sentence: The Stock Market, which was initially known as the "Kingston Stock Exchange," started stock trading operations on Monday, February 3rd, 1969, as restricted to brokers who traded both as agents and as principals.
Split into simpler sentences: The Stock Market, which was initially known as the "Kingston Stock Exchange," started stock trading operations on Monday, February 3rd, 1969. It was restricted to brokers who traded both as agents and as principals.