Sources: Slack is raising $200M at a nearly $4B valuation led by Thrive Capital
Business Insider : Tweets: @mattrosoff Tweets: Matt Rosoff / @mattrosoff : BTW Slack is now worth $3.7 to $3.8B. So if rumors true, $MSFT would've been paying a bit more than 2x mkt value. http://www.businessinsider.com/ ...
Context & Ripple Effects
This round caps a year of steep revaluation: Slack was in funding talks at a $2B-plus value in March 2015, closed up to $160M at $2.8B weeks later, and is now raising $200M at nearly $4B led by Thrive Capital. Business Insider's Matt Rosoff notes that at this price, Microsoft would have been paying more than 2x market value had it bought Slack.
The raise also puts a fresh lead investor on the cap table — Thrive Capital, which has been writing large checks elsewhere — ahead of the round's official confirmation.
First-order effects
- Slack's valuation roughly doubles versus the $2B-plus talks of March 2015, giving employees and early backers paper gains while diluting prior holders by another $200M of new money.
- Thrive Capital takes the lead position on one of the fastest-growing private software companies, a marquee logo for the firm's enterprise portfolio.
Second-order effects
- The rumored price set the floor for the confirmed close: weeks later Slack announced the same $200M round at $3.8B, alongside disclosure of 2.7M daily active users and 800K paid seats — metrics that justified the step-up.
- A higher private valuation raises the bar for strategics: by mid-2017 Slack was fielding acquisition interest from Amazon, Microsoft, Google, and Salesforce at a $5B post-money, and by 2018 it was raising $400M-plus led by General Atlantic at $7B+.
Third-order effects
- If the pattern holds, category-leading SaaS companies can stay private indefinitely on successive mega-rounds, with valuations compounding faster than any single acquirer's willingness to pay — pushing eventual outcomes toward IPO rather than early sale.
- Workplace messaging consolidates into a capital-intensive duel between independent Slack and bundled incumbents like Microsoft Teams, where each funding round buys runway but not immunity from platform competition.
The trend: Enterprise collaboration is splitting into a two-track race between venture-funded independents compounding through successive mega-rounds and suite incumbents bundling chat for free.