The treasuries aren't sold by the brokerage per se. They are being traded on the bond exchange, which are facilitated by the brokerages that you use. So for example, let's say you are using SAXO capital markets. you see on the bonds page that they are offering canada bond 10 year. These gov bonds are offered by the government themselves, so the Canadian government issues these bonds. These bonds are sold to whoever buys them, and then they become a creditor, or a bond holder, debtor etc. Now, this doesn't mean that the brokerage themselves are selling the 10 year canada bond, someone else is selling it on the exchange. So essentially, they are holding onto this security (the classification given to equities, bonds...) in their account, just like a stock, but now they wanna sell it for whatever reason that they have. So when you buy this bond on the brokerage, they help you to connect to this man/woman, and take your money, pay him/her, take a cut, give you the bond, and viola there you have it, your very own canadian 10 year bond. And this happens for all types of securities. Just think of it as a huge market, full of people who want to buy something and sell something. It's quite tedious to find within this crowd who exactly wants to buy/sell something you want/have, so the brokerage is the middleman that does everything for you, while taking a cut. Hope this helps!