Microsoft claims 20M DAUs for Teams, up from 13M in July, extending its lead over Slack, which in October said it had 12M; Slack closes down 8.35%
here's how that compares to rival Slack Mark Emem / CCN.com : Not Buying Slack in 2016 is Bill Gates' Best Call Ever as Microsoft Tech Advisor Kareem Anderson / OnMSFT.com : Slack fights back, says Microsoft's Teams numbers show low engagement Dale Walker / cloudpro.co.uk : Microsoft Teams surpasses 20 million daily users Todd Bishop / GeekWire : Microsoft Teams and other Office 365 services back online after untimely outage Duncan Riley / SiliconANGLE : Slack's shares plunge as Microsoft Teams passes 20M daily active users Microsoft 365 Blog : 5 attributes of successful teams Eric J. Savitz / Barron's Online : Slack Stock Slides as Rival Microsoft Teams Hits 20 Million Active Users Jon Swartz / MarketWatch : Microsoft Teams is making Slack investors nervous with its growth Tony Owusu / TheStreet : Slack Tanks as Microsoft Says Teams App Has 20 Million Daily Users Cal Jeffrey / TechSpot : Slack stock falls after Microsoft boasts 20 million Teams users Reuters : Microsoft Teams surpasses 20 million daily active users; rival Slack shares slip Carmen Reinicke / Business Insider : Slack plunges 11% after Microsoft's rival messaging platform extends its lead with 20 million daily active users Shaun Williams / Wccftech : Slack Technologies Better Watch Out - Here Comes Microsoft! Alex Wilhelm / Crunchbase News : Microsoft Teams Reaches 20M DAUs, Pushing Ahead Against Slack Ambhini Aishwarya / Reuters : Microsoft Teams surpasses 20 mln daily active users, up 50% from July Pradeep / MSPoweruser : Microsoft Teams has hit 20 million daily active users, nearly 8 million more than Slack! Mary Jo Foley / ZDNet : Microsoft says it has 20 million daily active Teams users Sean Endicott / Windows Central : Microsoft Teams hits 20 million daily active users Msmash / Slashdot : Microsoft Teams Hits 20M Daily Users, Up 50% in 4 Months Brandy Betz / Seeking Alpha : Slack -8.4% as Microsoft Teams hits 20M DAUs Tweets: Laurie Pottmeyer / @lauriepottmeyer : Microsoft Teams hits 20M daily users, up 50% in 4 months — Proud to be part of a team working so hard to create something awesome for our users. https://www.geekwire.com/... via @GeekWire Thanks: @oliviaandrus
Context & Ripple Effects
Four months ago Microsoft reported 13 million daily active users for Teams; in October Slack countered with 12 million of its own. Today Microsoft claims 20 million DAUs — a jump large enough that Slack shares closed down 8.35%, and Slack's response has shifted from competing on scale to arguing quality: per its own messaging, Teams' numbers reflect low engagement.
The structural difference behind the gap is distribution: Teams ships inside Office 365, while Slack sells standalone. Even Microsoft's own coverage underscores the trade-off — a recent untimely outage took Teams down alongside other Office 365 services, showing how tightly the product is bound to the suite.
First-order effects
- Slack investors repriced the stock immediately, closing it down 8.35% on the news that the rival's user base overtook theirs by roughly two-thirds within four months.
- Slack is forced onto defensive ground publicly, contesting whether Microsoft's DAU count measures engaged usage rather than conceding the scale race.
Second-order effects
- Competing on raw user counts becomes unwinnable for Slack when the rival bundles chat into an installed enterprise suite, so its pitch pivots to depth of usage and switching costs among existing paying customers.
- Enterprise buyers gain leverage: with Microsoft demonstrating rapid feature-and-user momentum inside Office 365, Slack faces pressure on pricing and bundling just to stay in procurement conversations it once led.
Third-order effects
- If the cadence holds — Microsoft reporting accelerating adoption each quarter while Slack argues about metrics — workplace chat consolidates around suite vendors, and standalone collaboration tools survive only where they integrate with, rather than compete against, the dominant productivity stack.
- Metric wars between platform vendors and point-solution rivals become a recurring investor event, pushing markets to discount self-reported DAU figures and demand revenue-quality signals instead.
The trend: Enterprise collaboration is consolidating around bundled productivity suites, leaving standalone tools like Slack to compete on engagement depth against rivals that distribute by default.