Jay Z 'forgot' he owned music streaming service Tidal

The rapper has a stake in music streaming service relaunched earlier this year

Rapper Jay-Z has numerous business ventures (Getty Images)

Jay Z accidentally “forgot” he owned music streaming service Tidal in court this week.

The rapper, real name Sean Carter, was in court over the disputed copyright of song “Big Pimpin’”.

Osama Fahmy claims Jay Z and Timberland, real name Tim Mosley, improperly licenced his deceased uncle’s composition “Khosara Khosara” for their 1991 hit.

Taking to the stand, Jay Z explained he was unaware the song had a sample within it.

He claimed checking the copyright over samples was “not what I do. I make music.”

Asked by his lawyer Andrew Bart to elaborate, Jay Z listed his companies and ventures, Vulture reported.

“I make music, I'm a rapper, I’ve got a clothing line, I run a label, a media label called Roc Nation, with a sports agency, music publishing and management. Restaurants and nightclubs ... I think that about covers it,” he told the court.

There was a pause before Mr Bart prompted: "I’m not so sure. You have a music streaming service, don’t you?"

"Yeah, yeah. Forgot about that," Jay Z reportedly deadpanned.

Tidal, a music service that promises users superior sound quality, was re-launched by Jay Z with much fanfare earlier this year. The service, which reportedly has roughly 700,000 subscribers, has experienced some difficulties – not the least that Jay Z forgets he has a stake in it.