A former guest shared: 'People go to the Vanity Fair party to be photographed - then they go to Madonna's to party in private.'
The party - that last year welcomed the likes of Jennifer Lawrence, Miley Cyrus, Brad Pitt and Angelina Jolie - may be Hollywood's hottest celebration but some people are 'annoyed' that her party is so exclusive.
A source added to the New York Post's Page Six column: 'Madonna's managed to usurp the Oscars, and she's not from the film business. Some people are annoyed that her party has skimmed the most famous people from the top.'
Meanwhile, the next few weeks will see the 56-year-old singer begin her promotion for her upcoming album and her representative has cited this as the reason for missing her own party.
They said: 'Madonna has been committed to performing on 'The Jonathan Ross Show' as well as various other promotion for months. Any Madonna performance naturally requires a lot of rehearsal - like Tina Turner says, 'We never do nothin' nice and easy.'
'I'm told that there will be as many stars as ever at mega manager [Guy's] party.'