* Euro rallies to $1.42, highest in 9-1/2 months
* Fed intends to buy $600 bln of bonds by end of Q2 2011
* Analysts see more dollar downside; BOJ meets Nov. 4-5 (Adds details, updates prices)
By Wanfeng Zhou
NEW YORK, Nov 3 (Reuters) - The U.S. dollar fell against the euro but rose versus the yen in volatile trade on Wednesday after the Federal Reserve unveiled plans to buy $600 billion in government bonds to help stimulate the economy.
The euro soared to a session peak of $1.42 on the EBS trading platform immediately after the Fed's announcement, the highest level since Jan. 20, as some investors said the total size of bond purchases was slightly bigger than expected.
Markets were generally priced for the Fed initially to commit to buying at least $500 billion in Treasury debt over five months.
"This is negative for the dollar," said Michael Woolfolk, senior currency strategist at BNY Mellon in New York. "Overall we are very much bearish on the dollar and there is absolutely no way you can look at today's Fed action as a positive."
The euro
The euro then briefly surrendered gains to trade below $1.40 as some investors reassessed the Fed's decision to buy about $75 billion in longer-term Treasury bonds per month until the second quarter of 2011. For details, see [ID:nN03287174]
"I don't think the Fed over-delivered." said Richard Franulovich, senior currency strategist at Westpac in New York.
"And beyond June, there's nothing, there no outlook. I am slightly underwhelmed. The dollar did sell off, but I don't think this spike in the euro has legs," he added.
The Fed said it would regularly review the pace and size of the program and adjust it as needed depending on the path of the recovery. In its post-meeting statement, the Fed described economic growth as "slow", and said measures of inflation were "somewhat low."
MORE DOLLAR DOWNSIDE
"After the dust settles, with the Fed the only major central bank with a bias toward easing, the dollar is vulnerable going forward," said Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington D.C. "Over the near-term, a dollar/euro near $1.45 is within the realm of possibilities."
Some analysts believe the euro can climb even higher. BNY Mellon's Woolfolk said "a euro/dollar at 1.50 by the middle of next year is not out of the question."
But some remained skeptical about the euro's outlook given renewed worries about the region's sovereign debt issues.
The dollar has lost nearly 8.0 percent versus a basket of major currencies <.DXY> since September on expectations that more monetary easing from the Fed would pressure U.S. yields and diminish the return on dollar-denominated assets.
Alan Ruskin, head of G10 currency strategy at Deutsche Bank in New York, said the Fed is "being pretty aggressive" at a time when recent economic data has beat expectations and global growth is still strong.
"The core medium-term strategy to look at long risk trades, particularly in the (emerging markets) world still funded with the U.S. dollar will remain unchanged," he said.
The dollar rose 0.6 percent against the yen to 81.13
The all-time low of 79.95 yen was still in focus and traders remained on alert for possible yen-selling intervention by Japanese authorities to weaken its currency.
The Bank of Japan meets on Nov. 4-5. The bank said it brought forward its policy review to this week from mid-November to heed calls to speed up the launch of its 5-trillion yen ($62 billion) asset buying scheme.
"Provided you see dollar weakness sustained against the major currencies, I think the yen is likely to participate, so we'll get another shot at 80 yen and below," Deutsche Bank's Ruskin said.
The Fed announcement followed a day after the widely expected outcome of U.S. midterm elections -- where the Republicans took control of the House of Representatives while the Democrats were set to hang on to the Senate. [ID:nN03266983]
The U.S. dollar index <.DXY>, a measure of the greenback versus a basket of six currencies, fell 0.5 percent. (Additional reporting by Gertrude Chavez-Dreyfuss, Julie Haviv, Nick Olivari and Steven C. Johnson;)