Under this scenario, clients for flexible office space are supplemented by enterprise users and could lead traditional leases to convert to flex.

Overall, WeWork is the top dog among operators, adding almost 11 million square feet year-over-year. Across over 700 operators, the top 10 account for 68% of the 71 million square foot market.

Other operators that aren’t in the top 10, but are among the fastest-growing include CommonGrounds, Venture X, Serendipity Labs and Common Desk.

Now, as competition tightens, operators are finding new business models in order to stand out from competitors and attract landlords. For example, some firms are entering in landlord partnerships to better share the rewards and risks.

Another model shows landlords offering their own flexible office spaces, such as Studio by Tishman Speyer.

“As occupiers become more sophisticated in engaging with flex providers, we expect that demand from larger users will fuel flexible space expansion,” according to the report. “Large users likely will identify the fluid, uncertain, volatile aspects of their business and use flex to reduce risky long-term lease liabilities.”