Reports suggesting China will move to ban Bitcoin have led to the cryptocurrency's value falling significantly. It's now down to $3,500, while it was sitting between $4,500 and $5,000 in recent weeks. China still hasn't confirmed if there will be a ban or severe restrictions.
Speculation regarding new regulatory action and other changes that'd negatively impact a cryptocurrency have repeatedly driven down values. Some of those cases turned out to be baseless, which could end up being true with the Chinese ban rumors.
Concerns about an impending ban increased when one of the largest exchanges in the country, BTC China, announced it would stop trading within the country (international transactions aren't affected).