GlaxoSmithKline (NYSE: GSK) is a much bigger company as of today.

The U.K.-based drug giant, which operates its U.S. headquarters in Research Triangle Park, said Friday that it had closed on the $3.6 billion acquisition of Maryland-based Human Genome Services.

GSK had worked with HGS to develop the lupus treatment known as Benlysta.

Some 87 percent of HGS shares ended up being tendered to GSK under terms of the deal. The tender expired at 5 p.m. EST on Thursday.

The deal values Human Genome at about $3.6 billion on an equity basis, or $3 billion net of cash and debt.

GSK has been pursuing HGS for three months and had resisted raising its officer. HGS had sought another buyer.

HGS agreed on the takeover following a prolonged battle in which it had put up a “poison pill” defense which would have diluted holdings if anyone attempted to acquire 15 percent or more of its stock without board approval.

Under the agreement, GSK said it gains full ownership of the drugs Benlysta for lupus, albiglutide for Type 2 diabetes and darapladib which is a possible treatment for atherosclerosis.

GSK’s higher offer followed the release of data from a cardiac safety study which was positive for albiglutide.

The company said it expects at least $200 million in cost synergies to be realized by 2015, and expects the transaction to be accretive to core earnings beginning next year.

(Bloomberg news and The AP contributed to this report.)

[GSK ARCHIVE: Check out a decade stories as reported in WRAL Tech Wire.]