After vowing to engage in a messy battle to take over gene sequencing company Illumina (ILMN) for $5.7 billion, Swiss drug maker Roche says regulators are now requesting more information about the deal.

The “second request” from the Federal Trade Commission seeks additional information about Roche’s microarray business, most likely reflecting antitrust concerns. The request delays any acquisition another 10 days after Roche complies with the request under U.S. law.   

Roche, which commenced a tender offer to acquire all outstanding shares of Illumina for $44.50 at the end of January, said it will work “closely and cooperatively” with the FTC as it conducts the review.

Illumina has long rejected the offer, calling it last month "grossly inadequate" and adopting a “poison pill” in defense.

In February, Roche said it would pursue the acquisition anyway, laying out a plan to nominate independent candidates for election to Illumina’s board to try and gain a majority over the Illumina board, making it easier to move forward with the acquisition.

Roche has already lifted its bid once in early January, first offering $40 a share. It has said Illumina has refused to engage in discussions.  

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