The acquisition of Pacific Biosciences of California by Illumina was always going to be a tricky one to get past the antitrust regulators. The US FTC was already looking into the deal, and now its UK counterpart, the Competition and Markets Authority, has provisionally concluded that the $1.2bn buyout could result in a substantial lessening of competition in the market for next-generation sequencing systems in the UK. This would result in “reduced choice, an increase in prices, deterioration in quality deterioration in service and/or loss of innovation”. Illumina responded to this fighting talk in its Q3 call yesterday, with chief executive Francis deSouza claiming, counterintuitively, that the acquisition is “pro-competitive and in the best interest of customers and the genomics industry”. Investors sent Illumina down 5% and Pacbio down 9% – at $4.77, stock in the latter is only marginally higher than it was before the $8-per-share takeover was announced last November. If the deal is disallowed Pacbio will be in trouble; it is unprofitable and will have to raise additional cash through some other means. The companies have until November 14 to respond to the CMA, and it will be intriguing to see whether divestments are mooted.