Group 1 - The U.S. stock market has a complex trading mechanism that is crucial for market participants to understand for better engagement in trading [1] - Regular trading hours are from 9:30 AM to 4:00 PM Eastern Time, Monday to Friday, with high market participation and active trading volume [1] - Pre-market and after-hours trading provide additional opportunities for investors, especially those with specific information or analysis, although they may have lower liquidity and higher costs [1] Group 2 - The U.S. stock market does not have fixed trading unit limits, allowing investors to trade in whole shares or fractional shares, thus lowering the investment threshold [2] - Various order types exist in the U.S. stock market, including market orders, limit orders, and stop-loss orders, each serving different purposes and risk management strategies [2] - Market orders execute immediately at the best available price, while limit orders allow investors to set specific buy or sell prices, and stop-loss orders help minimize losses [2] Group 3 - The U.S. stock market operates on a T+2 settlement cycle, meaning that the settlement of funds and securities occurs on the second trading day after the transaction [3] - Brokers must complete the necessary clearing procedures with clearinghouses to ensure accurate transfer of funds and stocks between buyers and sellers [3]