When someone says $300 million dollar company, it doesn't mean a company with $300 million dollars of revenue or profit per year. Generally, it means the valuation (based on any number of measures, ie. acquisition price, last traded price x number of shares outstanding, founders pulling a figure out of thin air, etc.) of the company, so revenue can be anywhere from $0 to $300+ million (generally around single-digit multiples), and profit can even be negative.