Oct 24 (Reuters) - Chinese aviation and shipping conglomerate HNA Group said on Monday it agreed to buy an about 25 percent stake in Hilton Worldwide Holdings Inc HLT.N from Blackstone Group LP BX.N for $6.5 billion.

HNA is buying the stake at $26.25 per share, representing a premium of 14.6 percent to Hilton's closing price on Friday.

Blackstone's holding in Hilton will be reduced to 21 percent after the deal closes in the first quarter of 2017, the companies said.

(Reporting by Ankit Ajmera in Bengaluru; Editing by Saumyadeb Chakrabarty) ((ankit.ajmera@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 80 6749 3067; Reuters Messaging: ankit.ajmera.thomsonreuters.com@reuters.net))