> If Coinbase is _guaranteeing_ you a 4% return, No, they are _promising_ you a 4% return - hardly the same thing. There is a non-zero risk that they'll go ou

> If Coinbase is _guaranteeing_ you a 4% return, No, they are _promising_ you a 4% return - hardly the same thing. There is a non-zero risk that they'll go out of business. Companies go out of business all the time, sometimes with no warning at all. I worked for a company that was for a short time the largest private company in the world. Within two years, the SEC showed up one morning, and told all the traders to perform an orderly liquidation, because the company was insolvent. If they go out of business, you might even lose some or all of your principal. Ask yourself this: when savings rates are around 1%, why do they have to offer 4% if this is riskless? Surely the efficient market hypothesis means that that extra 3% or so is what they perceive people will want for bearing this extra risk?