Mar 23, 2015 · 1 minute

Slack, the fast-growing enterprise collaboration software which has found fans across a wide array of technical and creative industries -- including here at Pando -- is reportedly seeking funding at a valuation that tops $2 billion, according to BloombergBusiness. The startup, which is the third company run by Silicon Valley journeyman Stewart Butterfield, would add to the $180 million in private cash it's already stuffed in its war chest.

When we last spoke to Butterfield, Slack was still a lowly single unicorn among the 50 or so US tech companies that have been valued at $1 billion or more over the past two years, according to CB Insights. But don't place too much weight on the company's outsized valuation. After all, Butterfield doesn't.

"It's arbitrary as fuck," Butterfield told Sarah Lacy on the PandoMonthly stage in San Francisco last month. "There’s no logic to what you get valued at.”

Arbitrary maybe, but not without importance. Checking that box next to "Unicorn status" not only grabs you headlines from the number-obsessed tech press. It also, according to Butterfield, prices you out of most acquisition offers. Of course that's only a problem if you plan to sell, and Butterfield, who in Flickr has already lost one startup baby to acquisition, is in this for the long haul and wants employees who feel the same way.

Watch him explain the tangled politics of valuations in the clip below:

[photo by Geoffrey Ellis]