Investors have lost billions of dollars on US penny stocks amid a rise in 'pump and dump' scams, according to reports from the Financial Times and other sources. These scams have particularly affected small US-listed Chinese stocks, often referred to as meme stocks, which saw sharp declines shortly after heavy promotion on social media. In July alone, seven Chinese stocks involved in such schemes wiped out a total of $3.7 billion. The increase in these fraudulent activities has raised concerns about the opacity, risk, and lack of investor protections in this market segment. Experts advise retail investors to exercise caution and consider safer investment options such as public index funds. Meanwhile, hedge fund investors are expressing frustration over opaque fees and are beginning to resist through their investment choices.