MANCHESTER UNITED CEO Richard Arnold will step down, the Premier League club said on Wednesday, ahead of the club's reported stake sale to British billionaire Jim Ratcliffe.

General counsel and board director Patrick Stewart, who has been with United for over 17 years, will be become interim CEO, allowing the club's future owners to take time to identify a new long-term CEO.

The English club's future ownership remained uncertain after the American Glazer family last year said they were looking at options for the 20-times English champions, including a new investment or a potential sale.

Reuters reported in October that Ratcliffe would pay more than $1.5 billion for a 25% stake in United were his bid for the iconic soccer club to be accepted by the Glazer family that controls it.

The Glazers have not yet reached a deal with Ratcliffe but one is expected to be finalised between the two sides in the coming weeks, a source told Reuters earlier this month.

Arnold was appointed CEO less than two years ago, when he took over from executive vice-chairman Ed Woodward and filled a role that had been left vacant since 2013.

Tasked with reviving the club's fortunes, Arnold in April last year brought on team manager Erik ten Hag, who has also come under intense pressure in recent months because of the club's lacklustre performance on the field.

Under Arnold's leadership, United posted record revenues and bagged a couple of major sponsorship deals, including a $1.1 billion Adidas kit deal for 10 more years in August.

Stewart, who will stay on his current role as general counsel, leads the club's liaison with governing bodies such as the FA and UEFA.

"My job will be to ensure that the club’s foundations remain stable while we embrace changes that can make us stronger over the long term," Stewart said in a statement.

Sky News was first to report the management changes on Wednesday.

Arnold will provide "transitional support" until the end of December, the club said, and they will start looking for a permanent CEO, United said in a statement.

United's New York listed shared were up 1.3% at $19.07 in premarket trading.