MongoDB shares plummeted as much as 11 percent on concern that ride-hailing service Lyft is shifting business to a rival cloud database service run by Amazon Web Services.

AWS said on Tuesday that Lyft is going "all-in" with its public cloud, a phrase Amazon typically uses when a company decides to pull over the vast majority of its technology infrastructure. Lyft has long relied on aspects of AWS, but is now expanding its use of Amazon services for serverless computing, containers for moving workloads and machine learning, the statement said.

The AWS announcement didn't mention anything about MongoDB, but Christopher Eberle, an analyst at Nomura Instinet, published a report on Tuesday, claiming that Lyft is "is quite dissatisfied with Mongo's performance and is in the process of a massive database migration."

Eberle, who has the equivalent of a sell rating on MongoDB's stock and a $63 price target, said he believes Lyft is a "marquee customer" of MongoDB.

A MongoDB spokesperson declined to comment. The company's annual report doesn't mention Lyft and says that no customer represents more than 10 percent of revenue.

The stock's selloff was its steepest since Jan. 10, when the shares dropped on news that Amazon was rolling out cloud-based database software called DocumentDB to directly compete with MongoDB. Dev Ittycheria, MongoDB's CEO, said at the time that "imitation is the sincerest form of flattery" and that "developers are savvy enough to distinguish between the real thing and a poor imitation."