Acer's planned $710 million acquisition of U.S. PC vendor Gateway won antitrust approval in the U.S. as the clock struck midnight Monday, Gateway said.

The time marked the end of a 30-day waiting period in which the U.S. Federal Trade Commission or the Antitrust Division of the U.S. Department of Justice may intervene or request additional time to review the deal for possible antitrust violations.

Not all transactions face antitrust scrutiny by the two U.S. agencies. Acer, of Hsichih, Taiwan, was forced to file with the agencies to notify them of its intention to buy Gateway and provide details of the proposed transaction due to the size of the deal.

At the end of the day on Monday, the waiting period ended, Gateway said in a filing to the U.S. Securities and Exchange Commission.

"The closing of the transaction remains subject to other customary conditions, including regulatory approvals in other jurisdictions which [Acer] anticipates will be satisfied over the next several weeks," Gateway said.

Acer agreed to buy Gateway in August. Once the acquisition closes, Acer will become the world's third largest PC vendor by shipments, at around 20 million desktops and laptops a year, and it will be transformed into a company with different PC brands.

The boards of directors at both companies have already signed off on the agreement.