"Those that are in [the market] are hoping we might be able to make a new high at the close of the year," said Robert Pavlik, chief investment strategist at SlateStone Wealth. "I think 2018 is going to be a pretty good year."
CNBC's survey of 14 major market strategists found the median estimate for the S&P 500 in 2017 is 2,590, about 3.6 percent below Thursday's levels. The median forecast for the S&P 500 next year is 2,850, about 6.1 percent above Thursday's levels. The S&P has rallied 20 percent this year.
The S&P 500 rose 0.2 percent to close at 2,687.54, with utilities and telecommunications leading advancers, and consumer staples the greatest laggard. The index closed within half a percent of its all-time highs hit on Dec. 18.
The S&P was also tracking for weekly gains as of Thursday's close. The index would close out the year with six straight weeks of higher trade for the first time since 1971.
Trading activity Thursday was again muted, with the second-fewest amount of shares transacted of any full trading day this year. U.S. markets were closed Monday for the Christmas Day holiday and will be closed next Monday for New Year's Day.
"I just think there's money that's still on the sidelines," said Marc Chaikin, CEO of Chaikin Analytics. "I think people are putting off selling until January because they can put off the gains [until the 2018 tax year]. There's a lack of sellers."
Meanwhile, the Nasdaq composite also added 0.2 percent to close at 6,950.16, as gains in big technology companies such as Apple and Facebook offset declines in biotechnology stocks such as Gilead and Amgen. The index is less than 1 percent away from its all-time high.
Information technology is the top-performing sector in the S&P 500 this year, up 38 percent since January.
"We're seeing a lot of these companies moving into the sweet spot ... Whether it's mobile advertising, whether it's online retail, whether it's streaming video," said Ark Invest CEO Cathie Wood during CNBC's "Halftime Report" on Thursday. "If you look at mobile advertising, both Facebook and Google, they own that, that's roughly 20 percent of total advertising."
Commodity prices, typically an indicator of global growth, also held near recent highs. Copper briefly rose more than 1 percent to its highest level in nearly four years. Oil held just below the psychologically key $60 level, a 2.5-year high which it touched earlier this week; crude settled up nearly half a percent at $59.91.