DUBAI- Qatar's sovereign wealth fund Qatar Investment Authority has reduced its stake in upscale jeweller Tiffany & Co as it rebalances its asset portfolio, according to Morgan Stanley, which managed the deal.

QIA sold 4.4 million shares in the jeweller through a block sale completed on Thursday, Morgan Stanley said in a statement, reducing its stake to 9.5 percent from 13 percent, according to Thomson Reuters data.

QIA has also recently cut its stakes in Russian energy giant Rosneft and Swiss bank Credit Suisse.

Market sources said the sale was valued at around $415 million.

Morgan Stanley did not give the value of the Tiffany share sale, or who bought the shares but said QIA had agreed to a 90-day lock-up.

"QIA has been a shareholder in Tiffany for over five years, and this transaction forms part of the portfolio rebalancing actions undertaken by QIA from time to time," Morgan Stanley said.

The sale comes after QIA and Glencore agreed this month to sell part of their stakes in Rosneft.

QIA's stake in Swiss bank Credit Suisse, one of its most prominent foreign investments, has also fallen, Reuters reported last month.

QIA has denied investor speculation it is having to cut back on overseas assets because Qatar's economy is slowing. Last month it said it would soon announce new international investments.

Qatar's economy has been under pressure since June 5 when Saudi Arabia, the United Arab Emirates, Bahrain and Egypt cut diplomatic and transport ties with Doha, accusing it of backing terrorism, a charge which Doha denies.

QIA has substantial cash reserves, estimated at around $300 billion, but some economists have speculated it might be called upon to support the economy.

Qatar's government deposited billions of dollars into the banking system in June and July to help offset a pull-out of funds by banks from other Arab states due to the diplomatic crisis.

(Reporting By Tom Arnold and Saeed Azhar; Additional reporting by Lance Tupper; Editing by Susan Fenton) ((; +97144536265; Reuters Messaging: