Air Products & Chemicals made its "best and final" offer on Thursday for rival industrial gas supplier Airgas, bumping the price by 7% to $5.9 billion, but the shares fell as investors bet it still was not enough to clinch a deal.

Air Products, seeking to put an end to a year-long takeover battle, offered $70 a share. That still falls below the $78 a share, or $6.5 billion value, that Airgas previously said it was worth.

Airgas shares fell 6.2% to close at $61.84 on Thursday, indicating market expectations Airgas may again reject the price. Air Products original bid was $60 in February.

"It is time to bring this matter to a conclusion and we are today making our best and final offer for Airgas," Air Products Chief Executive John McGlade said in a statement.

Airgas said it would review the new bid.

Airgas had said the previous bid of $65.50, which valued it at $5.5 billion, was too low and argued it was worth at least $78 a share.