So governments are issuing loads of debt, and central banks are buying most of it up. Doesn't that mean that any fundamental factors which should determine bond prices, such as the state of the economy, are largely irrelevant? If a government issues a load of debt the price will drop, if a central bank buys a load the price will rise. So trading bonds is a matter of anticipating what buying and selling activity there is? Which is probably very difficult because I don't think that central banks do much to indicate when they are about to buy.