The UK Competition and Markets Authority said Thursday that it has provisionally found that the proposed merger of Getty Images (GETY) and Shutterstock (SSTK) may lessen competition in the UK's editorial content supply, but not in the global supply of stock content.

The companies announced a merger deal in January to form a combined entity valued at about $3.7 billion.

The regulator gave the companies and interested parties until March 12 to respond to the interim report.

Getty Images and Shutterstock said they were "disappointed and disagree" with the CMA's provisional finding regarding the UK editorial market and plan to file responses by the March 12 deadline.

Shares of Getty Images were down by more than 6% in recent trading, while Shutterstock was more than 3% higher.

Price: 0.77, Change: -0.06, Percent Change: -7.23