Salesforce's acquisition of Slack is emblematic of a long-standing trend of defensive acquisitions by Big Tech and speaks to the impact of weak antitrust laws
Liz O'Sullivan / Fast Company : Tweets: @paulorf , @fastcompany , and @ophirgottlieb Tweets: Paulo Rodriguez / @paulorf : Amazing article that explains why tech companies in the collaboration space struggle to reach large size. Been there, can empirically confirm what's been said there. https://www.fastcompany.com/ ... @fastcompany : For startups and consumers both, the consolidation of innovative startups into the hands of just a few large firms should be troubling. https://f-st.co/iSFMxM0 Ophir Gottlieb / @ophirgottlieb : The dark reality behind Slack's billion-dollar sale to Salesforce https://www.fastcompany.com/ ... - Slack wanted to stay independent. But in a landscape dominated by tech giants, that proved impossible.
Context & Ripple Effects
The arc here runs fast: after the Wall Street Journal reported acquisition talks in late November, Salesforce confirmed the purchase within a week at $27.7B — its largest ever, and one that removes the most prominent independent challenger to Microsoft Teams. Fast Company's argument is that this was not a bet on collaboration software but a defensive move, part of a long-standing Big Tech pattern enabled by weak antitrust enforcement.
The later coverage gives the thesis an unusual amount of retrospective support: analysts found customers largely unmoved by Slack after integration, with its revenue growth sliding from 11.7% to 6.9% during 2022, and by mid-2025 Salesforce was blocking third-party firms like Glean from indexing Slack messages — the acquired asset functioning less as a product than as a wall around Salesforce's own data.
First-order effects
- Slack's independent trajectory ends: the company that forced Microsoft to build Teams is absorbed into a CRM vendor whose own customers, per later analyst reporting, showed little pull toward it.
- Enterprise buyers lose their most credible non-Microsoft messaging alternative, tightening Microsoft's position in workplace collaboration.
Second-order effects
- The 2025 restriction on Glean and similar enterprise-AI firms indexing Slack messages shows the acquisition's second life as a competitive moat — data access once open becomes gated by the acquirer.
- Collaboration-space founders read the outcome as confirmation that acquisition, not independent scale, is the realistic exit, reinforcing the consolidation dynamic the Fast Company piece describes.
Third-order effects
- If weak antitrust enforcement persists, defensive acquisitions keep converting potential disruptors into incumbent infrastructure — a pattern now extending from messaging into AI-era data access, where owning the corpus matters more than owning the app.
- The Slack case becomes a reference point for regulators weighing whether killer-acquisition doctrine should apply beyond classic horizontal mergers to data-and-platform deals.
The trend: Big Tech's defensive M&A is shifting from buying products to enclosing data ecosystems, with antitrust lagging each wave.