WASHINGTON—Stock exchanges intend to fire the contractor they hired to build a data warehouse for all U.S. stock-market activity, the latest sign of trouble for a project designed to detect trading fraud and causes behind wild swings in prices.

People familiar with the matter said the exchanges have lost confidence in Thesys Technologies LLC, a startup hired in 2017 to build the repository, known as the Consolidated Audit Trail. The Securities and Exchange Commission told the exchanges to create the database so it would have a complete picture of orders in the stock and options markets, a tool they have never had.

In November, Thesys launched a first stage of the project one year late and without the functionality that was expected.

The exchanges overseeing the contract confirmed Thursday that they are switching to a new vendor. The group said Thesys “is providing necessary services through the transition period.” The exchanges are evaluating how the switch will affect coming deadlines, including one that calls for the biggest brokerage firms to report orders to the data warehouse this year.

The Financial Industry Regulatory Authority, which regulates U.S. broker-dealers, is expected to take over the project, according to the people familiar with the matter. The committee of exchanges doesn’t have a signed agreement with Finra yet, the people said. A Finra spokesman declined to comment.