Shares in Echo Entertainment have plunged to a record low after Crown sold its stake in its casino-operating rival.

At 1155 AEST, Echo shares were down more than 10 per cent to $3.09, a slight improvement on their low of $3.03 shortly after the Australian market opened on Friday.

James Packer’s Crown on Friday confirmed it had sold its 10 per cent interest in Echo for $264 million, less than it paid for the shares.

The sell-off took place despite Crown gaining regulatory approval earlier this month to increase its stake in Echo to 23 per cent.

Mr Packer on Friday said Crown wanted to pursue its proposed hotel and high-rollers casino development at Sydney’s harbourside Barangaroo site without speculation about its stake in Echo.

The Crown Sydney development was a once-in-a-lifetime opportunity for the company, he said.

Echo’s The Star casino, at Darling Harbour, operates under the city’s only casino licence.

Echo’s shares were first listed on the Australian Securities Exchange in June 2011 at $3.07.

At noon AEST on Friday, Crown’s shares were down one per cent at $12.90.