Abbott Laboratories extended its cash tender offer to acquire all outstanding series B convertible perpetual preferred stock of Alere Inc.

Abbott launched the offer to acquire Alere's preferred stock at $402 apiece, plus accrued but unpaid dividends, on July 17. The tender offer, originally set to expire Aug. 11, has been extended to Aug. 31. More than 90% of the issued and outstanding shares of Preferred Stock had been tendered as of Aug. 11.

The acquisition valued at $5.3 billion is not conditional on the completion of the offer.

Barclays Capital Inc. is the dealer-manager for the offer, with D.F. King & Co. Inc. as information agent.