Wall Street, coming off Tuesday's 226-point tumble in the Dow Jones industrial average, lurched up and down throughout Wednesday's session. By late trading, it appeared to draw confidence from Germany's Continental AG's buy of Siemens AG's VDO auto parts unit, and better-than-expected quarterly earnings at Amazon.com Inc. and Boeing Co.

Still, some investors worried that deteriorating lending conditions in both the home mortgage and corporate debt markets will cork this year's huge stream of dealmaking. Buyouts usually involve taking on debt, and Wednesday, the banks raising funds for the turnaround of Chrysler Group had to postpone a $12 billion debt offer after investors balked at the deal's terms, according to people familiar with the situation who were not authorized to speak publicly.

Meanwhile, the National Association of Realtors on Wednesday confirmed that the housing market is far from recovery when it reported that sales of existing homes dropped 3.8 percent in June to the slowest rate in more than 4 years. The figure was worse than analysts expected, and followed data from the Mortgage Bankers Association showing mortgage applications fell for the first time in four weeks to a five-month low.

The market will likely remain rocky as Wall Street tries to assess whether problems involving risky home lending will hurt the broader economy.

"It's an open-ended unknown, and that's the problem," said Richard E. Cripps, chief market strategist for St. Louis-based broker Stifel Nicolaus.

In late afternoon trading, the Dow Jones industrial average rose 74.22, or 0.54 percent, to 13,791.17, after trading up more than 100 points and down more than 40.

Broader stock indicators also rose. The Standard & Poor's 500 index climbed 8.72, or 0.58 percent, to 1,519.76, and the Nasdaq composite index rose 11.76, or 0.45 percent, to 2,651.62.

Despite the gains in the major indexes, declining issues outnumbered advancers by about 10 to 7 on the New York Stock Exchange, where volume came to 1.67 billion shares.

Treasury bonds rose after the weak housing data prompted investors to buy safe government assets. As bond prices rose, the yield on the benchmark 10-year Treasury note fell to 4.91 percent from 4.95 percent late Tuesday.

Falling home prices have been making it harder for homeowners to refinance their homes, leading to more payment defaults and delinquencies. Home prices are likely to keep weakening, with values still unjustifiably high in many parts of the country, said Rob Lutts, President and CIO of Cabot Money Management.

"Does that mean that the stock market becomes totally unhinged? I don't think so. This is one factor," Lutts said. Still, he noted that the housing market downturn could easily cause a 5 percent to 10 percent correction in the stock market.

The dollar rose against other major currencies, while gold prices fell.

Light, sweet crude for September delivery rose $2.32 to $75.88 a barrel on the New York Mercantile Exchange, bouncing back from two straight days of steep declines after the U.S. government Wednesday said crude oil supplies fell last week.

Despite concerns about waning demand for risky debt, the acquisitions keep coming.

"Corporate balance sheets are very healthy. They're the healthiest they've been in 15, 20 years. I don't see that changing," Lutts said.

Siemens AG said it will sell its VDO auto parts unit to Germany's Continental AG in a $15.67 billion deal, and Merck & Co. agreed to buy NovaCardia Inc., a clinical-stage pharmaceutical company focused on cardiovascular diseases.

Merck, one of the 30 Dow companies, advanced $1.61, or 3.1 percent, to $53.33.

Though a few major companies have posted second-quarter financial results over the past couple weeks that missed Street forecasts, investors got some good news on earnings Wednesday.

Boeing was the biggest gainer in the Dow, rising $3.56, or 3.4 percent, to $107.36. The plane manufacturer posted a $1.1 billion profit in the second quarter, up from a year-ago loss, as it gets closer to overtaking its European rival Airbus in deliveries.

And Amazon.com surged $17.48, or 25 percent, to $86.73, after the Web retailer said its second-quarter profit more than tripled on strong sales of books, music and electronics worldwide.

With investors mainly focused this week on companies' earnings and forecasts for the rest of the year, they found little direction in the Federal Reserve's Beige Book. The report, which detailed mixed economic conditions in various parts of the country, said the overall economy kept growing at a moderate pace in June and early July, despite the ongoing housing slump.

The Russell 2000 index of smaller companies fell 7.59, or 0.93 percent, to 804.27.