The federally mandated antitrust review waiting period for Albemarle Corp.’s $6.2 billion acquisition of Rockwood Holdings Inc. has passed.

“This is another important step as we continue to make progress towards completion of the transaction with Rockwood to create a premier specialty chemicals company,” said Albemarle President and Chief Executive Office Luke Kissam.

Baton Rouge-based specialty chemicals maker Albemarle announced the acquisition on July 15. The company announced Wednesday that the antitrust waiting period ended at 10:59 p.m. Sept. 8.

Albemarle has offered $50.65 in cash and 0.48 shares of Albemarle stock for each share of Rockwood.

Albemarle and Rockwood shareholders must still sign off on the acquisition. Albemarle has said it expects to complete the deal in the first quarter of 2015.