On Monday, Twitter finally made its long anticipated announcement that Jack Dorsey, co-founder of the company and currently interim CEO, was indeed to become Twitter's next full CEO. The 38-year-old is currently also CEO of mobile payments company Square, a position that he will not vacate.

Dorsey made the announcement by fitting means, through a series of tweets detailing changes to the company's leadership, including his own appointment as CEO.

The announcement follows months of speculation after former CEO Dick Costolo left his position with Twitter in the summer, after a long series of disastrous months for the company with investors. As we noted last week, simply waiting to make the announcement of Dorsey's new permanent position with the company and disappointing investors' anticipation had caused Twitter's stock to slide.

"I am honored by the trust the board has put in me to continue to run the company," said Dorsey in a conference call with investors on Monday, according to the New York Times. "Over time, it became clear to us that Jack was not only meeting but surpassing our expectations of him as interim C.E.O. while running Square," added Peter Currie, who headed Twitter's CEO search committee, during the call.

According to an SEC filing, Dorsey, who now runs two Silicon Valley giants, will not be compensated directly in his new role at Twitter, but remains a major stockholder in the company nevertheless.

As Quartz noted, over the years Dorsey has changed his leadership style to focus more on high-level decisions, rather than micromanagement. But while that may free up Dorsey's time to deal with running both Square and Twitter, straddling both top positions may make Square's rumored path towards an IPO much more difficult.

Meanwhile, since Dorsey's last turn at the helm of Twitter ending in 2008, the company has grown much more massive, with over 4,000 employees and offices in more than 30 countries.

That's not to mention the challenges Dorsey will face after a year of disaster, including Twitter's leadership being fragmented, its board losing credibility with investors, and its stock price -- despite rising almost six percent as of the mid-afteroon after Dorsey's announcement -- still being valued at less than half of its post-IPO high in January 2014.

However, several new products and possible major changes may be launched soon under Dorsey, including a possible end of the 140-character limit and a real-time events-focused media and news product dubbed "Project Lightning," which has long been under development. Whether those changes lead to a turnaround for the company or more disaster is yet to be seen.

There have been successful Silicon Valley CEOs who have run more than one company simultaneously -- most notably Steve Jobs with Pixar and Apple and Elon Musk with SpaceX and Tesla. Now in his own dual-CEO role, Dorsey could either join their esteemed ranks, or Twitter and Square will both suffer more setbacks.