Michael Dell and Silver Lake Management LLC won’t sweeten their $24.4 billion offer to take Dell Inc. private, people with direct knowledge of the situation said.

Dell and Silver Lake are ruling out an increase because the $13.65-a-share offer they made in February represents a fair and significant premium to where the stock would trade if the deal fell apart, said one of the people, who asked not to be identified because the process is private.

Institutional Shareholder Services is preparing to make a recommendation to shareholders on founder Michael Dell’s buyout proposal. The investor advisory firm is leaning against the deal, people familiar with the matter said this week, and that would increase the likelihood that investors will oppose it at a shareholder meeting July 18.

Michael Dell, who founded the PC maker 29 years ago, believes he can keep control of the company in the long run even if he fails to take the company private, said one of the people familiar with the situation.

Representatives for Dell and Silver Lake declined to comment.