(Updates with closing prices, adds quote and auction)
By Daren Butler
ISTANBUL, Aug 5 (Reuters) - Turkish shares fell on Wednesday, weighed down by losses in index-heavy banks, as investors cashed in on the sector's 24 percent rise since the end of June and after Moody's said it will review ratings.
Bonds held steady after gains which took the benchmark bond yield to a record low of 9.92 percent on Tuesday after a tap of the bond lured strong demand on expectations that Turkey's aggressive interest rate-cutting cycle will continue.
The ISE National 100 index fell 1.78 percent to 43,899.44, paring this week's gain to 3 percent. The main share index has rallied almost 20 percent since the end of June.
Banks, which account for about 40 percent of the benchmark index, fell for a second day following a Moody's Investor Services statement on Tuesday that it has put Turkish banks on review, mainly for their local-currency deposits.
Garanti Bank, the third-biggest listed bank, fell 2.78 percent to 5.25 lira before it released its results after the market's close. Garanti posted net profit of 769 million lira in the second quarter, beating an average forecast of 741 million lira in a Reuters poll.
Yapi Kredi, the lender part-owned by Italy's UniCredit SpA, was among the biggest losers on the exchange, falling 6.13 percent to 3.06 lira. Analysts said Tuesday's stronger-than-expected earnings failed to justify the share's recent gains.
Analysts also cited a rise in bad loans and provisions on its balance sheet as factors weighing on the stock. Koc Holding , Yapi Kredi's main owner, fell 4.92 percent.
Media-to-energy group Dogan Holding jumped 8.87 percent to 1.35 lira after it said it was in talks with OMV on the sale of its stake in fuel retailer Petrol Ofisi, which climbed 8.73 percent to 6.85 lira.
A sale would bring much-needed cash for the embattled Dogan Holding, whose media unit Dogan Yayin is facing some $500 million in tax fines, said Hasan Sener, an analyst at Oyak Securities. OMV is the second-biggest stake holder in Petrol Ofisi.
Dogan Yayin and Hurriyet Gazetecilik, a newspaper publisher, rose 2 percent and 6.4 percent, respectively.
Turkish Airlines rose more than 9 percent before closing up 7.5 percent at 2.58 lira on hopes of wider expansion after saying it would start flying to Australia in 2011.
Its growth strategy has captured investors' attention at a time when the rest of the aviation sector is shrinking, nearly tripling the value of its shares this year, said Onur Mutlu, head of research at Gedik in Istanbul.
Investors also expect Turkish Airlines to post an increase in its second-quarter profit when it reports earnings at the end of the month, Mutlu said.
The lira firmed to 1.457 against the dollar on the interbank market, versus the previous day's 1.467.
The Central Bank bought $30 million at a forex-purchase auction on Wednesday against bids of $185 million, bank data showed. The bank introduced the auctions on Tuesday as the lira hit a 10-month high against the dollar.
The benchmark May 11, 2011, bond yield was flat at 10.09 percent.
The Treasury on Tuesday sold 843.5 million lira of the May 11, 2011, benchmark at an average yield of 10.1 percent, lower than a forecast of 10.35 percent, and giving a fresh boost to government paper in the secondary market.
"The combined results of the auctions this week ... suggest that concerns over the Treasury's ability to fund a wider budget deficit this year have been overdone," said Royal Bank of Scotland analyst Timothy Ash.
"It also suggests that foreigners, largely underinvested in Turkish local markets, are beginning to step up to the plate and put money to work in Turkey," Ash said. (Reporting by Thomas Grove, Ayla Jean Yackley and Selcuk Gokoluk; Editing by Ron Askew)