* U.S. dollar hit across the board, DXY near all-time low
* Euro/dollar above $1.46, poised to push towards $1.50
* Risk of profit-taking seen before Easter holiday (Updates prices, adds comments, detail, adds to byline)
By Wanfeng Zhou and Steven C. Johnson
NEW YORK, April 21 (Reuters) - The dollar fell broadly for a third straight day on Thursday as record low interest rates and the crushing weight of the U.S. budget deficit pushed it closer to an all-time trough against major currencies.
The dollar's slide accelerated days after Standard & Poor's slapped a negative outlook on the United States' top AAA credit rating. The agency said a downgrade was possible if authorities can't slash the massive U.S. budget deficit within two years.
That prompted investors, from fund managers to foreign central banks that hold trillions of dollars in assets, to opt for anything but the U.S. currency.
"The combination of loose monetary policy and chaos on the fiscal front has people very worried," said Boris Schlossberg, head of research at GFT Forex in New York. "That fear is being reflected in the dollar."
Mohamed El-Erian, co-chief investment officer of PIMCO, with $1.2 trillion in assets under management, said, "Absent problems elsewhere in the world, history and economics suggest that America's current fiscal and monetary policy stance will put continued pressures on the dollar."
The dollar index, a gauge of the greenback against six advanced country currencies, fell to 73.735, its lowest level since August 2008. Analysts said that sets up a possible run toward its record low of 70.698 touched in March 2008.
The euro soared to a 16-month high above $1.46 before easing to $1.4550, while the dollar fell 0.8 percent to 81.82 yen. The Australian dollar rose above $1.07, its highest in nearly three decades, as Australia's 4.75 percent interest rate and its role as a supplier of raw materials to booming Asian markets attracted investors.
Some investors fear a fragile U.S. economic recovery could sputter if the White House and Congress agree to cut the deficit with significant spending cuts or tax hikes. That would likely force the Federal Reserve to hold interest rates at record lows even as other central banks raise them.
"There is no clear sign that the U.S. is going to raise interest rates, and that is causing the dollar to depreciate by the day," said Jonathan Xiong, who helps manage about $30 billion at Mellon Capital Management in San Francisco.
Underwhelming employment and manufacturing data on Thursday underlined the sluggish nature of the U.S. recovery and the difficulty facing the Fed, traders said.
STRONG DOLLAR POLICY?
The European Central Bank raised interest rates this month for the first time since 2008 and is expected to do so again. Investors also expect currencies in China and other emerging markets to rise more quickly as authorities start relying more on stronger exchange rates to offset inflation.
Analysts said the euro was on course for a move toward $1.50 if the current momentum continues, despite the possibility of a Greek debt restructuring.
Talk that China may invest in Spain had investors shrugging off worries for now about euro zone debt.
The United States has historically insisted that a strong dollar was in the country's interest. Market analysts, though, say dollar weakness may be good news now insofar as it helps revive exports and encourages debt reduction and saving.
Last year, President Obama pledged to double export growth by 2015, a policy that would benefit from a weaker dollar.
"I don't think the U.S. is actively seeking a weaker dollar, but they're not unhappy with it either," Brown Brothers Harriman strategist Win Thin told Reuters Insider. "At the margins, it certainly helps exports and helps growth. As long as asset markets hold up, I think they're OK with this."
But some global investors may not keep blindly buying U.S. assets that carry increasingly more risk but persistently low returns.
"At some point along the line, people are going to realize it's absurd to the lend money to the United States government at 30 years in U.S. dollars at 3 or 4 or 5 or 6 percent interest," influential investor Jim Rogers told Reuters Insider.
Washington's borrowing costs have risen since late 2010 but the 30-year Treasury bond yield remained historically low at 4.47 percent. Debt-strapped euro zone countries such as Greece have to pay nearly four times that just to borrow money for five years.
Where things go from here may depend on Asian central banks. Since Monday, the euro has vaulted from $1.4155, and analysts said few in the market were brave enough to counter insatiable euro demand from Asian sovereigns.