Stocks rose for a fifth day on Friday on hopes Europe was on course to solve its debt problems, but investors warned of sharp reversals if real solutions failed to materialize.

Treasury Secretary Timothy Geithner urged EU finance ministers to leverage their bailout fund to better tackle the debt crisis and to start speaking with one voice, but there was no agreement on what steps to take.

There are still a lot of open-ended issues out there, which means this situation will remain pretty fluid, said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia. All of what we just gained in the last five trading sessions could be given back.

On Thursday stocks rallied as the world's leading central banks agreed to boost short-term dollar funding for banks, easing investor fears about the European financial system.

The Dow Jones industrial average <.DJI> gained 58.65 points, or 0.51 percent, to 11,491.83. The Standard & Poor's 500 Index <.SPX> gained 3.70 points, or 0.31 percent, to 1,212.81. The Nasdaq Composite Index <.IXIC> gained 8.36 points, or 0.32 percent, to 2,615.43.

The S&P 500 <.SPX>, up about 5 percent so far this week, could post its best weekly performance since early July.

United Technologies Corp is lining up financing for a major acquisition in the United States, according to people with direct knowledge of the matter.

The U.S. industrial conglomerate is tapping the credit market for funds that could top $20 billion, said one of the sources. Its shares slipped to $75.30. For details, see

U.S. consumer sentiment inched up in early September, but Americans were gloomy about the future. A gauge of expectations fell to its lowest level since 1980.

BlackBerry maker Research In Motion Ltd slid 19 percent to $24.08 a day after it reported a steep drop in quarterly profit and offered little hope of a turnaround soon.

General Electric Co gained 1.4 percent to $16.31 after forming two new joint ventures in Russia that the largest U.S. conglomerate said on Friday could generate $10 billion to $15 billion in new revenue over the next few years.

(Editing by Kenneth Barry)