You are technically correct that you can't just login to your broker one day and dump 5% onto the market - but there are ways to sell that amount of stock witho

You are technically correct that you can't just login to your broker one day and dump 5% onto the market - but there are ways to sell that amount of stock without crashing the price. A Secondary Offering is one way. It's basically doing an IPO over again but for an already public company. You can also sell directly to hedge funds/mutual funds etc. They have the opposite problem, wanting to acquire a large stake but being unable to because submitting an order for 0.1% would send the price to infinity.