* Moody's rating cut on Japan dents sentiment
* Regional big caps, financials tumble
* Indonesia, Philippines see outflows
By Viparat Jantraprap
BANGKOK, Aug 24 (Reuters) - Southeast Asian stock markets fell on Wednesday after ratings agency Moody's downgraded Japan, making investors wary of risky assets and dampening regional sentiment.
Markets failed to sustain early gains that were fuelled by speculation the Federal Reserve may signal further moves to support the struggling U.S. economy in Chairman Ben Bernanke's speech on Friday in Jackson Hole, Wyoming.
Losses in some markets, including Indonesia , were capped when local buyers stepped in to buy blue chips, brokers said.
"Net foreign selling, it seems, can't intimidate local buyers. The Japan downgrade is Moody's adjusting to Fitch and S&P. It would mainly affect Japan rather than other countries," said Jemmy Paul, head of research at Waterfront Securities Indonesia.
Indonesia's index ended down 0.9 percent, with foreign outflows of $57 million, adding to a combined $291 million in the previous three sessions, Thomson Reuters data showed.
Stocks in Singapore dropped 1.6 percent, Southeast Asia's worst on the day. Losses for Malaysia and Thai stocks were smaller of around 1 percent each. The Philippines inched down 0.2 percent.
Asian shares fell on Wednesday ahead of Bernanke's speech, while Japanese shares sold off on Moody's downgrade.
Asian stocks excluding Japan as measured by MSCI were down 1.16 percent by 0924 GMT.
Southeast Asian stocks have lost much of their recent upward momentum and trade below previous highs, including all-time highs for Malaysia set in July, Indonesia and the Philippines early this month, as investors are less optimistic across the board.
Market big-caps led losers. Singapore's top lender DBS Group dropped 3.9 percent to the lowest since November, 2009 and Malaysia's CIMB Group Holdings fell 2.4 percent to the lowest since August, 2010.
Indonesia's coal miner Adaro Energy plunged 5.7 percent and Philippine Long Distance Telephone (PLDT) , fell 3.3 percent, reversing a 3.9 percent surge on Tuesday when foreign investors bought stocks for its dividends.
Thai banks fell, with the biggest Bangkok Bank sliding 2.3 percent, amid expectations that rising interest rates would take a pause later this year.
The Bank of Thailand raised its policy rate a quarter of a point to 3.50 percent on Wednesday, a move widely expected by economists. It also said the policy rate was getting nearer to normal levels (Additional reporting by Andjarsari Paramaditha in Jakarta; Editing by Jason Szep) For Asian Companies click; For Asia-Pacific News click; For South East Asia Hot Stock reports, click;
SOUTHEAST ASIAN STOCK MARKETS Change on day Market Current Prev Close Pct Move Singapore 2719.90 2765.15 -1.64 Kuala Lumpur 1469.15 1482.37 -0.89 Bangkok 1046.43 1057.28 -1.03 Jakarta 3847.02 3880.46 -0.86 Manila 4366.45 4375.39 -0.20 Hanoi 396.68 401.28 -1.15 Change on year Market Current End prev yr Pct Move Singapore 2719.90 3190.04 -14.74 Kuala Lumpur 1469.15 1518.91 -3.28 Bangkok 1046.43 1032.76 +1.32 Jakarta 3847.02 3703.51 +3.87 Manila 4366.45 4201.14 +3.93 Hanoi 396.68 484.66 -18.15 Stock Market Volume (shares) Market Current Volume Average Volume 30 days Singapore 488,853,000 432,768,047 Kuala Lumpur 188,951,700 159,002,103 Bangkok 4,625,665 5,173,462 Jakarta 3,905,302,000 5,697,887,217 Manila 722,529 646,957 Hanoi 27,501 27,329