London, March 14 (IANS) A sex tape, rumoured to be featuring actress Mischa Barton, is being circulated around Hollywood and online porn companies are bidding for it.The X-rated footage reportedly shows the "Notting Hill" actress having sex with a man wearing just a grey hoodie, and the content comes with a price tag of $500,000, reports dailymail.co.uk.Kevin Blatt, who is Hollywood's sex-tape broker, says he was approached by a third party with the video and it's currently being shopped around "porn valley"."I know that at least three large online porn sites have reviewed it and they're all seriously considering the offer. I've seen stills from the video, it's clearly Mischa in my opinion. She's seen performing a sex act on a guy," he said.If the footage becomes public, it could affect Barton's emotional health, said a source."This is the last thing Mischa needs. Her name has been dragged through the mud enough times, she doesn't need a sex scandal right now," the source said.