US Officials: China Refuses to Help Stop Investment ScamsThe Chinese government snubbed a U.S. request for help in cracking down on a string of alleged investment frauds that have cost Americans billions, outgoing Securities and Exchange Commission Chairman Mary Schapiro told ABC News. The lack of cooperation has stymied efforts to recoup investor losses, she said, in one of the largest sprees of alleged financial crimes in recent memory -- one that has gone largely unnoticed by most Americans. "The consequence is it's very much more difficult for us to prove our cases," Schapiro said in one of her final interviews before leaving the post, which will be broadcast tonight as part of an ABC News investigation airing on "World News with Diane Sawyer" and "Nightline." WATCH the 'Nightline' report on alleged Chinese investment scams. More than 100 China-based companies have now been de-listed, have left the NASDAQ and New York stock exchanges, have been denied listing, or have withdrawn applications, all following allegations of fraud or accounting irregularities, the ABC News investigation found. https://abcnews.go.com/Blotter/us-investors-lose-billions-alleged-chinese-stock-schemes/story?id=18164787