AWS plays a pivotal role in stock trading app development by providing a suite of services that can significantly improve the user experience. For instance, real-time data updates powered by AWS AppSync can provide users with up-to-the-minute stock market information, which is crucial for making informed trading decisions in a stock market app. AWS's scalability, a key factor in trading app development, allows the app to handle large volumes of data and high traffic loads during peak trading hours without compromising performance. This ensures that the stock trading app remains reliable and efficient, enhancing the overall user experience.