Read More Oil market to ring in more gloom with 2016
The S&P 500 ended Wednesday at 2,063, just 0.2 percent higher on the year, and a little more than 3 percent below the all-time high of 2,134 it reached in May. The Dow, off 117 points Thursday at 17,603, is still negative, down 1.2 percent for the year. But Nasdaq is outperforming, up nearly 7 percent year to date, and it is home to some of the brightest stars in the market.
Netflix for instance was up 140 percent for the year, while Amazon.com was up 122 percent. Even volatile biotech outperformed, with the IBB iShares Nasdaq Biotech ETF up 12 percent. However, once darling Apple was down 4.6 percent, in what could be its first negative year since the market collapse in 2008.
Of the major global equity indices, the major U.S. indexes are closest to their recent highs. The German DAX, for instance, is 13 percent away from the high it hit in April, and the Nikkei is off 9 percent from its June high.
In the emerging world, the volatile Shanghai stock market is 31 percent below its June high, and Russia's stock market is nearly the same amount below its May high.
Read More The bond market is sending off a troubling signal
Some analysts point to the fact that a flat year could mean a higher following year, like in 2012, when the S&P was up 13 percent, after 2011's flat performance. The S&P 500 was truly unchanged that year, ending just 0.0025 percent lower, so a flat close is not unprecedented in this bull market.
"It reminds us a lot of 2011, which was a tough year and when we think of it … having given up the (2015) 2,311 year-end target just a few weeks ago when we realized a strong fourth-quarter rally was not likely to happen. In acceptance of that we considered this year as predominantly an unwinding process that will lead to a platform for a rally sometime in the first quarter," said John Stoltzfus, chief investment strategist at Oppenheimer Asset Management.
Stoltzfus is sticking close to his former 2015 target in 2016. He sees the S&P closing out the year at 2,300. The strategist does not foresee a big pullback early in the year, something some technicians say is possible.
"If we were to have a big downdraft we'd have to have some sort of catalyst for it, and that doesn't seem to be on the horizon," he said. Stoltzfus said the Fed has made it clear it will be cautious in raising rates, and that is not a risk now for the market.
Two things that "spoiled" the market's progress in 2015 were falling oil prices and a strengthening dollar, said Stoltzfus. Oil could continue to move the equity market but he expects there to be economic benefits from lower oil as well.
The S&P energy sector lost 24 percent in the past year and was the worst performing sector, followed by materials, which were down nearly 10 percent.
Read More Countdown with Cashin: Watch for this year-end phenomenon
Stoltzfus said the dollar should continue to gain relative strength against emerging markets, but he does not expect the dollar to rise all that much more.
"On a fundamental basis, among developed countries, the dollar is probably richly valued now. We don't think the dollar is in a secular trend of strength. We think the dollar is in a cyclical trend of strength and typically ahead of the Fed raising interest rates, the dollar begins to rise," he said.
The Fed raised its target fed funds rate by a quarter percent from zero on Dec. 16, and it has projected four hikes next year. The market is pricing in fewer hikes, and economists are expecting two to three more rate increases next year.
Bank of America Merrill Lynch expects the S&P 500 to reach 2,200 at year end. Jill Carey Hall, BofA equity strategist, said one of the biggest risks to that forecast could actually be the upside — and it's because the bull is aging.
"One of the biggest risks could be to the upside. We're calling for a year of muted returns," she said. Hall said one of the big questions is how late in the bull cycle the market is. "We found that typically at the very end of the bull market you typically get very strong gains. … The biggest risk is you get that big euphoria-driven rally you get later in a bull market. The obvious risks are more on the macro side if global growth doesn't accelerate and worsens or oil prices were to see leg downward. Those would be two of the biggest risks for the market."
Read More 2016 could be another big year for tech: Trader