The SEC has temporarily suspended stock trading for Smart Digital Group and QMMM Holdings over potential price manipulation. | Credit: Chip Somedivilla / Getty Images. Key Takeaways The SEC has temporarily suspended stock trading for Smart Digital Group and QMMM Holdings. Both companies recently announced plans to start investing in crypto. The regulator flagged suspicious social media posts that may have manipulated the market. On Friday, Sept. 26, the U.S. Securities and Exchange Commission (SEC ...