Tech workers’ favorite communications tool, Slack, is losing ground to its biggest rival, Microsoft Teams, which has copied its way into popularity. In other words, Slack has the same problem as Snapchat, which has suffered from its bigger rival Facebook’s relentless appropriation.

Slack’s market share among the world’s largest companies is mostly flat, adoption rates are declining, and a bigger portion of these companies indicate they plan on leaving the service, according to a new survey by market research firm ETR, which asks chief information officers and other leaders at the world’s biggest organizations* where they plan to spend their company’s tech budget.

Meanwhile, Teams is seeing increased market share, relatively higher adoption rates, and low rates of defection, according to the data.

Aside from potentially upsetting Slack’s high-flying, newly public stock, the situation points to a larger issue of innovation in the tech industry, which is increasingly dominated by only a few juggernauts. Politicians, including Sen. Elizabeth Warren (D-MA), have criticized the companies for creating what’s known as “kill zones,” where they either acquire or kill all their competitors. The result is that the best ideas and products are concentrated within existing large tech companies, further entrenching their dominance and potentially stifling future innovation.

Slack, which is currently trading below its first-day opening price, has been beset both by smaller companies hoping to improve upon it and tech giants trying to copy and replace it. Microsoft, at one point, had even considered buying Slack. Instead, nearly four years after Slack’s debut, Microsoft launched Teams, which has since adopted many of its competitor’s functions, including the basic premise of creating an online office space for coworkers to collaborate and communicate.

The situation was similar with Facebook, which after failing to buy Snapchat began to copy it, feature by feature. Facebook did this with impunity because it’s not really possible to copyright what software does — you can only copyright the code itself. Since products like Slack and Microsoft Teams or Facebook and Snapchat are built on different platforms, the code for each is likely distinct, so copying features is fair game.

As Marketplace’s Tony Wagner put it at the time, “There’s more than one way to skin a cat, and there’s more than one way to put a dog nose over your face.” Snap suffered from having a competitor — and copier — whose reach was much bigger than its own.

And Microsoft is already familiar with coming late to market with a product, then copying, underpricing, and scaling its way to success. Back in 2015, it released Microsoft Power BI to compete with Tableau, a data analytics and visualization company that had gone public a couple of years before. Microsoft’s less expensive option for data analytics — though some said it wasn’t as good — helped tank Tableau’s stock price.

Tech titans like Microsoft, Google, and Amazon have existing user bases that are many times bigger than the newer companies they sometimes compete with. These giants can also afford to charge less in order to beat out the competition.

Here’s a look at how these factors have helped changed major companies’ use of Teams and Slack:

Overall, the portion of new adoptions is declining for both Teams and Slack, but Teams’ user base is much larger — so it’s more likely to be a smaller share of its overall users.

And of course, ETR’s study is necessarily small, with only a few hundred respondents from major public and private companies mentioning their use of Slack or Teams, so it’s not definitive. Still, the trend is strong and is a warning sign for the newly public Slack, which touted its adoption among “more than 65 companies in the Fortune 100” in its IPO filings.

Slack declined to comment, citing its quiet period surrounding its public filing.

A Microsoft spokesperson wrote of the report, “Customers see Teams as a great deal because it’s part of Office 365, with deep integration into the other Office apps and services.”

Another reason Teams’ use is expanding rapidly: Since many companies already have Office 365, which includes business staples like Word, Excel, and OneDrive, in addition to Teams, they basically get the workplace communication software for free.

“Large organizations spent the last three years moving to Azure [cloud services] and to Office 365,” Thomas DelVecchio, founder and chief executive officer of ETR parent company Aptiviti, told Recode. “They’re going to go with Teams unless there’s a dramatic difference with price and performance.”

“Teams was tolerable as a Slack alternative”

Indeed, cost, as well as integration with Office 365, tended to be the main reasons ETR survey respondents gave for using Teams over Slack. (Slack also has Office 365 integration.) The general consensus among respondents was that Teams was not as good as Slack, but that it had gotten a lot better than it had been and was for the most part an acceptable alternative.

Niel Nickolaisen, chief information officer at employee recognition company OC Tanner, recently moved his entire company over to Teams in an attempt to standardize communications. Previously, he had wanted to switch everyone to Slack, but because the company had an existing enterprise contract with Microsoft, Teams was almost free.

“It got to the point where Teams was tolerable as a Slack alternative,” Nickolaisen, who took the ETR survey, told Recode. “If they’re fundamentally close, nearly free is compelling enough to make the switch.”

Slack’s big competitors will certainly challenge its path forward, but its journey isn’t impossible. It could focus on winning more small companies as clients and perhaps lean into its popularity among early adopters and trend-setters.

For what it’s worth, Snap and Tableau are so far doing fine despite Facebook and Microsoft’s competitive pressure. Snap is trading up 160 percent this year — though still below its offer price — and its business performance has prompted several analysts to upgrade its stock. And Salesforce snatched up Tableau last month for $15.7 billion, about a 45 percent premium on the company’s market value, all in the hopes of taking on none other than Microsoft.

It’s true that the $28 billion workplace software market has room for multiple competitors. But as we know, once a large tech company establishes a lead in a given market, it’s difficult to unseat it.

* Organizations surveyed are in the Forbes Global 2000, Forbes’ list of the 225 biggest private companies, and the US government.

** ETR looked at decreases and increases of 6 percent or more. Less than that was indicated as flat usage.

Recode and Vox have joined forces to uncover and explain how our digital world is changing — and changing us. Subscribe to Recode podcasts to hear Kara Swisher and Peter Kafka lead the tough conversations the technology industry needs today.