NEW YORK (CNN/Money) - The Dow Jones industrial average rallied Thursday, bringing its three-day gain to more than 668 points, as investors poured into Citigroup and J.P. Morgan Chase after a $30 billion loan to Brazil brightened prospects for companies doing business in Latin America's biggest economy.

Strength in drug, technology and consumer products stocks powered a broad market rally linked to expectations that the Federal Reserve stands ready to cut interest rates again.

But analysts called Wednesday's gains vulnerable to the kind of selloffs that have defined the market's two-and-a-half year tumble.

"We recommend investors sell into strength because of the uncertainties lurking," Kari Bayer, senior U.S strategist at Merrill Lynch, told CNNfn's Halftime Report.

The Dow industrials surged 255.87 points, or 3 percent, to 8,712.02, in a third consecutive triple-digit advance that narrowed its year-to-date loss to 13 percent.

For the Dow, Wednesday's was its biggest three-day point gain since March 17, 2000, according to Ned Davis Research. In a last gasp of the bull market, the blue chips rose 784 points over three sessions that day.

Also up over the last three sessions, the Nasdaq rose 35.62, or 2.8 percent, to 1,316.52 and is down 33.2 percent this year. The Standard & Poor's 500 index gained 28.69, or 3.3 percent, to 905.46.

Analysts said the International Monetary Fund's $30 billion bailout package, which was bigger than expected, cuts the odds of an economic collapse in Brazil like the one that hit Argentina earlier this year.

J.P. Morgan Chase (JPM: up $2.34 to $26.38, Research, Estimates) and Citigroup (C: up $2.38 to $33.90, Research, Estimates), big lenders to Brazilian companies and citizens, were among the Dow's biggest gainers.

"Investors are very comfortable that the U.S will not let Brazil go the way of Argentina," said Mark Fitzgibbon, banking analyst at Sandler O'Neill. "The IMF has eased worries about Brazil's ability to pay its debt later this year."

FleetBoston Financial (FBF: up $1.71 to $23.62, Research, Estimates), with large exposure to Brazil, also advanced.

"This is a confidence booster for the markets," said Denis LaPlante, a banking analyst at Fox-Pitt Kelton. "What we're seeing is a reversal of some of the negative confidence."

Gains in Johnson & Johnson (JNJ: up $2.06 to $54.57, Research, Estimates), Procter & Gamble (PG: up $1.92 to $90.85, Research, Estimates) and IBM (IBM: up $2.44 to $71.61, Research, Estimates) also lifted the Dow.

The stock market is on track for a third straight year of losses for the first time since 1941. But Fred Sears, chief investment officer at Investor Capital Funds, said most of the market is still too expensive to merit sustained gains.

"We're very bearish," said Sears, who likes shares of State Street (STT: Research, Estimates), Taro Pharmaceutical (TARO: Research, Estimates), and Krispy Kreme Doughnut (KKD: Research, Estimates). "We think there will be rallies, but they will be short-lived."

Sears expects more corporate layoffs and calls the Dow industrials vulnerable to the kind of correction suffered by the Nasdaq, which is down 74 percent from its all-time high hit in March 2000.

Several retailers reported soft July sales numbers Thursday, including Dow component Wal-Mart Stores (WMT: up $0.81 to $49.19, Research, Estimates), the No. 1 retailer, whose sales growth slowed. Another Dow retailer, Home Depot (HD: down $1.12 to $27.14, Research, Estimates), was the indicator's biggest loser.

Only one other Dow stock fell: McDonald's (MCD: down $0.86 to $22.50, Research, Estimates). Health officials in Canada said a Canadian man died of the human strain of mad cow disease.

Monsanto (MON: up $1.39 to $17.34, Research, Estimates), the maker of herbicides, is joining the Standard & Poor's 500 index. It replaces Palm (PALM: down $0.16 to $0.82, Research, Estimates), the maker of handheld computers, whose shares have tumbled to under $1 from $100 two years ago.

New economic data showed that wholesale prices fell in July as businesses facing slackening demand cut the costs of goods. The government's Producer Price index slipped 0.2 percent last month, led by a slide in auto prices. Economists expected a slight gain.

Separately, the Labor Department said the number of Americans filing new claims for unemployment benefits fell by 15,000 to 376,000 last week.

Overseas, Asia's markets edged lower while Europe's markets rose. The dollar rose against the euro and yen. Treasury securities slipped while crude oil futures were little changed.

More stocks rose than fell. Advancing issues on the New York Stock Exchange topped declining ones more than 2-to-1 as 1.6 billion shares traded. Nasdaq winners topped losers nearly 10-to-7 as 1.5 billion shares traded.

Next week brings two big market events. Federal Reserve policy makers meeting Tuesday are expected to leave short-term lending rates unchanged at 40-year lows. But central bankers, facing a string of weak economic data, may signal that lower rates lie ahead, a development that's generally good for stocks.

Wednesday marks the deadline for 947 company executives to sign off on the accuracy of their financial statements. Click here to see which companies have already done so.