Aluminum products maker Arconic's board of directors is mulling an $11 billion acquisition offer it received last Friday from buyout firm Apollo Global Management, according to people familiar with the matter.

The offer is at a small premium to where Arconic shares are trading, adding pressure on the U.S. company to decide if it will remain independent after President Donald Trump's imposition of aluminum tariffs drove up its costs this year and weighed on business prospects.

Apollo's offer values Arconic at between $23 and $24 per share, one of the sources said. Arconic shares ended trading on Monday at $21.45. Arconic had $6.3 billion in total debt and cash of $1.46 billion as of the end of June.

Another bidding group, comprising buyout firms Blackstone, Carlyle Group, Onex, and Canada Pension Plan Investment Board, has yet to submit an offer for Arconic, and it is not clear whether it will submit a bid to rival Apollo's in the coming days, the sources said.

Arconic has not yet set any firm bid deadline and no deal is imminent, though the company is hoping to reach a decision on whether it will sell itself by the time it holds its investor day next month, according to the sources. It is not clear whether more bids from other parties will emerge.

The sources asked not to be identified because the deliberations are confidential. Arconic, Apollo, Blackstone, Carlyle and Canada Pension Plan Investment Board declined to comment, while Onex did not immediately respond to a request for comment.

Arconic's products, which are made of aluminum, titanium or nickel, are used around the world by aerospace, automotive, commercial transportation and packaging manufacturers.

Arconic, which was spun out of Alcoa Corp in 2016, said in February it would carry out a "strategy and portfolio review."

In August, Arconic announced it was considering selling its building and construction systems unit, which makes facades, windows and framing products. The announcement came one year after a major fire broke out at London's Grenfell Tower apartment complex, where the company's Reynobond PE panels were used in the cladding. More than 70 people were killed in the blaze.

Activist hedge fund Elliott Management Corp, which won board representation at Arconic last year following a proxy contest, has been instrumental in pushing the company to explore a sale, sources have said.