Slack just raised a whopping $427 million to become a $7.1 billion company. Now, it has to defeat Microsoft (MSFT)

Slack, the very popular work chat app, has raised $427 million in venture capital, at a valuation of "more than $7.1 billion."
All told, Slack has raised about $1.27 billion in venture capital — including in a $250 million mega-round led by Softbank in the September of 2017, which gave it a $5 billion valuation at the time.
This valuation would make it that much more expensive for a larger tech company to buy it, and thus, at least a little less likely. But it's also been coy about a potential IPO, raising questions about the master plan.
All the while, Microsoft has been reinforcing Microsoft Teams, its own work chat product.

Slack, the work chat app that's become a poster child for Silicon Valley startup success, is on something of a hot streak.

First, Slack bought the intellectual property to Atlassian's HipChat, which had been one of its chief rivals. Then, no less than Microsoft recognized Slack as a major rival to the Microsoft Office suite in an official regulatory filing.

Now, Slack can add one more to its win column, as it takes in a whopping $427 million in an investment round led by Dragoneer Investment Group and General Atlantic, with participation from T. Rowe Price, Wellington Management, and others, including its existing roster of investors.

This investment, in turn, leads to two other figures of interest: Slack is now valued at "

All of that said, this funding round raises some questions for the future of Slack.

This $7.1 billion valuation makes it that much more unlikely that Slack will get bought up by a big tech company. If Amazon, for example, were to revisit its reported interest in buying Slack, it would likely have to pay a big premium over that valuation to seal the deal. Even for a gigantic tech company like Amazon, that would be a hefty price tag.

At the same time, Slack has so far played coy about a possible IPO, declining to announce any plans one way or the other. With so much money going into the startup, though, some kind of exit seems like it will have to come sooner rather than later.

And all the while, Slack is facing down the continued threat of Microsoft, whose Microsoft Teams product comes bundled with the mega-popular Office 365 productivity suite for businesses. While Slack has its fair share of super-fans and champions, Microsoft wields significant might in this market, and the startup has its work cut out for it.

Microsoft hasn't taken this lying down, either, and has made moves to make Teams more competitive with Skype — most recently, launching a free version of Microsoft Teams to hook in smaller groups, and hopefully lure them to the paid version.

So while the ability to raise so much cash, so quickly, is a definite feather in the company's cap, it now falls on Slack to show the world that it can take on its much larger competitor...and win.