(Recasts, updates prices, changes byline)
By Lucia Mutikani
NEW YORK, March 24 (Reuters) - The dollar rose against a basket of currencies on Monday after a surprise jump in U.S. existing home sales gave optimism over the economic outlook a small boost, as an enhanced offer for Bear Stearns buoyed stocks and risk appetite.
But uncertainty over whether JPMorgan Chase & Co's (JPM.N: Quote, Profile, Research) fivefold increase of its initial offer for Bear Stearns (BSC.N: Quote, Profile, Research) shares would succeed caused the dollar to give up the bulk of its gains against the euro in thin post-Easter Sunday trade, traders said.
Still, the New York Board of Trade's dollar index, which tracks the dollar's performance against a basket of six major currencies, recorded gains for a fourth consecutive session.
"To the extent that it (the home sales report) is not a decline, it represents a little bit of a positive for the U.S. housing market. It's certainly a short-term relief for the dollar and overall the U.S. outlook," said Brian Dolan, chief FX strategist at Forex.com in Bedminster, New Jersey.
Sales of existing U.S. home sales rose in February for the first time since July, data showed. For details, see [ID:nN24323265].
The dollar raced to a session peak of 100.89 yen <JPY=>, the highest since March 14, and well off a nearly 13-year low of 95.77 yen posted last week, according to Reuters data. It last traded at 100.67, up 1.1 percent from late on Friday.
The dollar index was up 0.1 percent at 72.859 .DXY, after earlier rising to 73.194, the highest since March 12.
The greenback's rise against the Japanese currency was largely driven by news that JP Morgan had upped its offer for Bear Stearns to $10 per share from $2 previously. This boosted U.S. equities and investors' appetite for riskier trades.
At the same time, the New York Federal Reserve said it would provide $29 billion in term financing to facilitate JP Morgan's acquisition of Bear Stearns and will form a privately managed company to oversee assets pledged as collateral.
CAUTION OVER BEAR STEARNS DEAL
But traders said there were still concerns that the deal might not close and introduce some level of uncertainty yet again in the market. Those worries helped the euro recoup some losses against the dollar.
"There is still some uncertainty about what is going to happen with any gains and losses on the Bear Stearns debt that the Fed has underwritten," said Greg Salvaggio senior vice president of capital markets at Tempus Consulting in Washington.
"That has encouraged some people to sell the dollar and take a little bit of profit from this sharp move down from the level near 1.58 (on euro/dollar)."
In late New York trade, the euro was flat at $1.5425 <EUR=> after slipping to a session trough of $1.5343 and still off a record high of $1.5905 touched last week.
Traders said there was also interest to buy the European single currency below $1.54, limiting its losses.
"It's an illiquid market. Some people are looking to buy some cheap euros below 1.54, which has really prompted this move up, but I would not read into any direction until we get the Europeans back tomorrow," said Salvaggio.
Most financial markets were shut for the Easter holidays on Monday and will reopen on Tuesday.
Against the Swiss franc, the dollar jumped 1.0 percent to 1.0190 francs <CHF=>, recovering from record lows at 0.9637 last week. The euro surged 1.2 percent to 155.44 yen <EURJPY=>.
The rise in U.S. stocks lifted the high-yielding Australian and New Zealand dollars against their American counterpart.
"The good news today suggests that risk appetite may be coming back because it feels like the worst might be behind us for the time being," said Boris Schlossberg, senior currency strategist at DailyFX.com in New York. (Additional reporting by Gertrude Chavez-Dreyfuss; Editing by Jonathan Oatis)