Blackrock, the world's largest asset manager, has warned in its latest spot bitcoin exchange-traded fund (ETF) filing update of the potential for bitcoin to be classified as a security by the U.S. Securities and Exchange Commission (SEC), state regulators, or court rulings. "If a digital asset is determined or asserted to be a security, it is likely to become difficult or impossible for the digital asset to be traded, cleared or custodied in the United States through the same channels used by non‑security digital assets," Blackrock cautioned.