Financial assets that a central bank must buy and sell are nothing new.

Historically, the U.S. Federal Reserve has focused on short-term Treasuries, but quantitative easing has seen it buy mortgage-backed securities and high-quality commercial paper (debt instruments issued by corporations) in large quantities. In general, central banks often hold gold and foreign currencies.

Separately, the U.S. government holds reserves of some vital commodities, such as the Strategic Petroleum Reserve. The Treasury also holds reserves of foreign currencies and special drawing rights. Many foreign governments go further, with large-scale sovereign wealth funds that include stocks, natural resources (Canada has its own strategic reserve, for maple syrup), and other assets.

As for bitcoin, Senator Cynthia Lummis of Wyoming has introduced a bill that would require the Treasury to create a $67 billion (in current values) stockpile of the cryptocurrency, an idea that Republican presidential candidate Donald Trump supports, saying it would be “a permanent national asset that benefits all Americans.” The bill may not be serious legislation - it is unlikely to pass.