Just before Facebook's initial public offering, its founder and CEO Mark Zuckerberg wrote a letter to investors reminding them that the social network was "not originally created to be a company." He continued this trend internally, chiding employees who brought up questions about revenue during discussions of how to build new products. But according to a lengthy report in The Wall Street Journal, after a poor start on the stock market and a painful slide during his company's first two quarters, Zuckerberg decided to buckle down, grow up, and start focusing on the nitty-gritty of the business.

He got trusted engineers to give up coding and start working on spreadsheets and mobile ads instead. He began taking face-to-face meeting with important clients like McDonalds. And he embraced more ads in both the news feed and in the company's mobile products. The result has been a strong turnaround that has boosted the stock to new highs. For investors, it's good news. For users worried about more ads in Facebook and Instagram, it might seem like quite the opposite.