Emerson Electric (EMR) on Monday defended its offer to acquire the shares of Aspen Technology (AZPN) that it does not already for $265 per share following criticism by activist investor Elliott Investment Management that the price "substantially undervalues" the company.

Emerson said its tender offer is "compelling," and represents its "best and final price." The company said it spent three months negotiating the offer price with Aspen, and that an independent special committee of its board has unanimously recommended the transaction.

Emerson said Elliott is a "short-term stockholder who has acquired stock in AspenTech for the purpose of merger arbitrage."

The all-cash Emerson tender offer is set to expire on March 10.

Elliott Investment Management did not immediately reply to MT Newswires' request for comment.

Emerson shares rose 2% in premarket trading, while Aspen Technology was 3% lower.