Calling his effort to stop the sale of Dell Inc. (DELL) to company founder Michael Dell and private equity firm Silver Lake Partners “almost impossible,” activist investor Carl Icahn has said that he will not make any further effort to prevent the sale. Dell shareholders are scheduled to vote on the Michael Dell-Silver Lake proposal on Thursday.

In a statement Monday morning, Icahn said:

I realize that some stockholders will be disappointed that we do not fight on. However, over the last decade, mainly through 'activism' we have enhanced stockholder value in many companies by billions of dollars. We did not accomplish this by waging battles that we thought we would lose.

Icahn also said he continues to oppose the deal because it undervalues the company and that he plans to seek appraisal rights. The offer that Dell’s shareholders will vote on values Dell at $24.75 billion, or a per share price $13.75. The buyout team also has agreed to pay a special dividend of $0.13 a share at or before the time the deal closes and to pay a third-quarter dividend of $0.08 per share.

Dell’s share opened down slightly Monday morning, having closed at $13.83 on Friday. The stock’s 52-week range is $8.69 to $14.64.