Arcadium Lithium stock is up 30.5% as of 10:10 a.m. ET today in response. Other lithium mining stocks are following Arcadium higher, with notable outperformers including Standard Lithium ( SLI 10.40%) and Piedmont Lithium ( PLL 11.00%), up 11.5% and 18%, respectively.

Key Takeaways Rio Tinto announced Wednesday that it has agreed to acquire Arcadium Lithium in an all-cash deal at $5.85 per share, expanding its access to a key ingredient of electric vehicle (EV) batteries.

Rio Tinto's acquisition of Arcadium Lithium boosts market exposure but adds risk. Learn more about why RIO is a buy and ALTM is a hold.