Facebook Inc (NASDAQ:FB) and Tesla Motors Inc (NASDAQ:TSLA) led the market’s gains on Monday as both companies marked major milestones in the growth of their market capitalizations. Tesla’s rose over $20 billion for the first time, while Facebook’s climbed over $100 billion—something it hasn’t done since before its initial public offering in May 2012.

Facebook

Facebook’s stock history

Seth Fiegerman of Mashable reports that Facebook Inc (NASDAQ:FB) had a valuation of $100 billion on the second market before the company’s IPO. Then it raised $16 billion through that IPO, which gave it a value of around $104 billion.

However, the social network’s value declined right after its IPO, and it only started rising again recently after the company’s most recent earnings report. In September Facebook Inc (NASDAQ:FB) shares hit their all-time low of $17.55 per share, and the social network’s market cap fell under $50 billion.

Facebook and Instagram

One of the reasons shares of Facebook took off is because of signs that the company is successfully making the shift to mobile. The latest data from comScore shows that user engagement on the social network is still growing. JPMorgan analysts downplayed the impact on Facebook from competing services. Interestingly enough, they lumped Instagram in with those competing services.

Of course Facebook Inc (NASDAQ:FB) owns Instagram. Seeking Alpha contributor Bryan Waters notes that it looks as if the social network is following the same strategy with Instagram as it did with its main platform. The company said earlier this year that it is allowing Instagram to grow its user base before it begins to monetize the service.

Investors have been clamoring for Facebook to monetize Instagram for months, and Waters seems to believe that following a similar strategy to Instagram could provide a similar surprise in future earnings reports from Facebook. He also notes that by waiting, Facebook Inc (NASDAQ:FB) management has a chance to figure out the best way to go about monetizing it.