Arcadium Lithium (ASX: LTM) shares are defying the weakness in the lithium industry on Thursday and surging higher.

At the time of writing, the $10 billion ASX lithium stock is up 8% to $9.14.

As a comparison, here's how other lithium stocks are performing:

• The Core Lithium Ltd (ASX: CXO) share price is down over 2%
• The Liontown Resources Ltd (ASX: LTR) share price is down 4%
• The Pilbara Minerals Ltd (ASX: PLS) share price is down 3.5%
• The Sayona Mining Ltd (ASX: SYA) share price is down 3.7%

Why is this ASX lithium stock outperforming?

Today's gain has been driven by some news relating to its proposed blockbuster takeover by mining giant Rio Tinto Ltd (ASX: RIO).

As a reminder, the two parties signed a definitive agreement late last year under which Rio Tinto will acquire Arcadium Lithium in an all-cash transaction for US$5.85 per share (A$8.71 per share).

This represented a sizeable 90% premium to the prevailing Arcadium Lithium share price and valued the company at approximately US$6.7 billion (A$10 billion) at the time.

Since then, the Australian dollar has fallen against the US dollar, making Rio Tinto's offer of US$5.85 per share now worth approximately A$9.41 per share, which values the ASX lithium stock at approximately A$10.8 billion.

What's the latest?

Well, the good news for shareholders is that the takeover deal received a big boost overnight.

According to the release, the Committee on Foreign Investment in the United States has concluded its review of the proposed acquisition of Arcadium Lithium by Rio Tinto and determined that there are no unresolved national security concerns.

This means that merger control clearance has now been satisfied or waived in Australia, Canada, China, Japan, South Korea, the United Kingdom, and the United States. In addition, investment screening approval has been satisfied in the United Kingdom.

What's left?

There are still a few hurdles left for Rio Tinto to jump before it can add this ASX lithium stock to its portfolio.

The release notes that transaction remains subject to investment screening approvals in Australia, Canada, and Italy, as well as other customary closing conditions.

But if all goes to plan, Arcadium Lithium advised that it expects the proposed transaction to close before middle of 2025.

Unlike Arcadium Lithium's shares, Rio Tinto's shares aren't rising on the news. At the time of writing, the mining giant's shares are down slightly to $115.67.