But it carries more risk. It may not continue to pay 3%. In a financial crisis the money may not be there any more, the companies may go bankrupt en masse for e

But it carries more risk. It may not continue to pay 3%. In a financial crisis the money may not be there any more, the companies may go bankrupt en masse for example, or companies that were previously thought to be safe may not be able to meet their obligations. There is no sort of guarantee here, and the SIPC guarantees are supposed to be about making sure investors end up with the securities they purchased, not making investors whole if their investments turn out to be worthless. It is precisely this kind of bundled 'derisked' derivatives which caused the last financial crisis (those were sold as very low risk mortgage debt , these are corporate debt).