Oppenheimer's John Stoltzfus raised his year-end target 200 points on Monday, based on expectations of better earnings and economic growth.
U.S. economic growth of about 2 to 2.5 percent — even without any added federal stimulus — and improving global growth means "corporate revenues and earnings could rise further [and] warrant higher prices for stocks," Stoltzfus, chief investment strategist at Oppenheimer Asset Management, said in a note Monday.
His new 2,650 target reflects a 7 percent gain from Friday's near-record close of 2,472 and is the second-highest of the 16 strategists surveyed by CNBC. Only Morgan Stanley's 2,700 target, officially a 12-month forecast, is higher.
In a separate report Monday, Morgan Stanley's Mike Wilson reiterated his 2,700 target and noted how sell-side U.S. equity strategists on average expect the S&P to end the year below its current level.
Including the Oppenheimer forecast, the median year-end S&P 500 target of 16 strategists surveyed by CNBC is 2,475, just three points above where the S&P closed Friday.
Part of Stoltzfus' case for stocks to rise is a decline in U.S. dollar strength.
"A modestly weaker dollar can help to improve the competitiveness of S&P 500 US multinational companies doing business across the globe," he said. "This could well serve earnings seasons in the quarters ahead."
Check out CNBC's latest market strategist survey.
The U.S. dollar index has fallen more than 2 percent for July, tracking for its first five-month losing streak since April 2011.
Stoltzfus attributed weakness in the U.S. dollar to expectations for a slower pace of Federal Reserve rate hikes, rather than a "loss of confidence" in the Trump administration's ability to "execute its stimulus agenda."
JPMorgan's head of U.S. strategy and global quant research, Dubravko Lakos-Bujas, also pointed to dollar weakness on July 21 when he raised his S&P 500 target by 150 points to 2,550.
"Our analysis suggests for every ~2% decrease in USD, S&P 500 EPS has historically been revised up by ~1%," Lakos-Bujas said. He also cited tax reform as a reason to expect stock-price gains.
S&P 500 companies are expected to post earnings-per-share growth of 10.8 percent for the second quarter, topping the 8 percent growth analysts expected on July 1, Thomson Reuters I/B/E/S data showed Friday. More than half of S&P 500 companies have already reported quarterly results.
Stoltzfus also raised his earnings-per-share estimate for the S&P 500 by $4 to $129 Monday.
U.S. gross domestic product grew at a 2.6 percent annualized rate in the second quarter, up from a downwardly revised 1.2 percent in the first quarter, the U.S. Bureau of Economic Analysis said Friday.
Oppenheimer maintained overweight recommendations on technology, health care, consumer discretionary, industrials and materials sectors. The firm is underweight energy, utilities and telecommunications.