The UK Competition and Markets Authority (CMA) has announced that Illumina’s $1.2 billion acquisition of Pacific Biosciences is potentially anti-competitive, delaying the expected conclusion of the deal until fourth quarter 2019. The CMA said the deal could remove Illumina’s biggest competitor, leaving limited alternatives available for customers.

The CMA added that while there are suppliers entering the market in the future, it is unknown how competitive their technology will be.

While the CMA can only stop sales in the UK, the markets of the UK, US and China are so large that a veto in one of them would likely spell the end of the acquisition entirely. In addition, the delay to completion of the takeover could spell trouble for PacBio, already struggling to reach a profit in recent months.

The CMA will refer the takeover for an in-depth phase two investigation if the parties fail to address its concerns.