The Standard & Poor's 500 Index may have jumped 17 percent so far this year and 148 percent from its March 2009 low, but that doesn't mean it won't keep rising, experts say.

In the past, when stocks have begun the year so strongly, they have ended the same way, according to CNBC.

"The bears keep getting steamrolled, and the bulls keep adding to positions," Walter Zimmerman, senior technical analyst at United-ICAP, said.

Editor's Note: See the Disturbing Charts: 50% Unemployment, 90% Stock Market Crash, 100% Inflation

He has been bearish, but is starting to give in.

"Looking at the near-term indicators, it looks like all we're likely to get here is a bull market correction," Zimmerman told CNBC. "And that's a ways away."

The S&P 500's break through 1,665 Monday puts the next target at 1,790, he says. That represents an 8 percent increase from Thursday's close of 1,651.

Strategas analysts Chris Verrone and John Kolovos see smooth sailing ahead for stocks. "The rally continues to look orderly in our view," they wrote in a commentary obtained by CNBC. "Trending markets can stay 'overbought' for very long periods of time."

Goldman Sachs analysts foresee continued stock strength as well. They just boosted their year-end forecast for the S&P 500 to 1,750 from 1,625 previously.

U.S. economic strength and global central bank easing will propel the increase, the analysts said.

"If interest rates stay low despite better growth, then upside to S&P 500 may be greater than we currently forecast," David Kostin, Goldman's chief U.S. equity strategist, wrote in a commentary obtained by CNBC.

Editor's Note: See the Disturbing Charts: 50% Unemployment, 90% Stock Market Crash, 100% Inflation