U.S. Stocks Rise as Banks Gain on Europe's Moves to Tame Crisis

"There's great potential reward, nevertheless great risk," James Paulsen, who helps oversee about $333 billion as chief investment strategist at Minneapolis-based Wells Capital Management, said in a telephone interview. "If you take Europe out of the picture, valuations could jump dramatically. If there's disappointment, we can have a sizable decline."

Period where rating agencies have to be more cautious

"This is a period where rating agencies have to be more cautious," Eric Teal, chief investment officer at a glance Citizens Bancshares Inc., which manages $4 billion in Raleigh, North Carolina, said in a telephone interview. "It's conceivable that there will be more downgrades. There's some optimism building there that if Europe has a bold enough plan, they could put some of the problems behind. We're however skeptical because of the many structural problems."

SuccessFactors Inc. surged 51 percent to $39.75. SAP AG, the largest maker of business-management software, agreed to buy the company for $3.4 billion in cash to keep pace with rival Oracle Corp. in the cloud-computing market.