By Dan Strumpf

The Dow industrials were poised to end 2014 with their sixth straight year of gains, fueled by an expanding U.S. economy, growing corporate profits and persistently low interest rates.

Despite a decline Wednesday, the blue-chip index is on pace to rise 8% for 2014. Its ascent is the longest since the bull market of the 1990s, which saw the average climb for nine straight years through 1999.

U.S. stocks were bolstered by an expanding, if uneven economic recovery, surprising strong earnings growth and a Federal Reserve that remained accommodative even as it wound down a postcrisis stimulus program. Low bond yields allowed corporations to borrow cheaply and at a record clip. A crash in oil prices fattened consumer wallets, although it also dented the fortunes of a resurgent U.S. energy industry.

It’s been another great year, said Bill Smead, chief investment officer at Smead Capital Management, which manages about $1.1 billion. U.S. stocks still have room to run in 2015, he added. We’re still early in this economic recovery.

Still, stocks were ending 2014 with a whimper rather than a bang. The Dow Jones Industrial Average recently was down 83 points, or 0.5%, to 17902 Wednesday, reversing a small early-day gain. Traders attributed the losses to last- minute selling as investors close the books on the year. Trading volumes were light ahead of the New Year’s holiday Thursday, when financial markets the world over are closed.

The S&P 500 fell 14 points, or 0.7%, to 2066. The broad-market index is tracking a climb of 11.8% this year, its third straight year of gains.

Many investors say the factors that propelled U.S. stocks higher should remain in place into 2015. Economists expect the U.S. economy to grow 2.9% in the year ahead, up from forecasted growth of 2.2% this year. Corporate profits, meanwhile, are set to rise another 7.2% next year, according to analysts polled by FactSet.

The road to 2014’s gains was bumpy. The year’s pullbacks were often steeper, although investors quickly jumped in following selloffs to take advantage of cheaper valuations. Some investors said that stocks were due for a correction, defined as a drop of 10% or more from a recent peak, but one never came to pass. A rise in bond yields, which move in the opposite direction of prices, was also widely predicted.

The Dow closed at a record high 38 times, while the S&P 500 did so 53 times. Markers of volatility fell to multiyear lows over the summer, while trading volumes slumped. Instead of rising, the yield on the benchmark 10-year Treasury note fell by 0.857 percentage point to 2.173%, as investors snapped up safe-haven U.S. debt.

There’s a lot to be bullish about, said David Seaburg, head of sales trading at Cowen and Co. in New York. People are generally positive about the backdrop of what’s happening from an economic perspective, from a job growth perspective.

Below the surface, some signs of turbulence emerged. Many investors were caught flat-footed by the decline in bond yields, which led to a surprise surge in income-oriented investments like utility stocks. High-growth corners of the market like biotechnology stocks saw big swings. A 46% plunge in oil prices dealt a blow to energy companies and tripped up a popular bet on the U.S. shale boom.

Market watchers say 2015 won’t be without its challenges. The Fed is slowly reining in its loose monetary policy. In October, it stopped expanding its bond-purchase program and is poised to raise interest rates sometime in 2015. While the U.S. economy is growing at an expanding clip, Europe’s is showing signs of trouble and China’s long-booming economy has been cooling.

At the same time, stocks grew more expensive this year and remain pricey compared with historical averages. The S&P 500 index now trades at 16.4 times forecasted earnings over the next 12 months, compared with 15.4 a year ago, according to FactSet. The average over the last 10 years is 13.2.

The U.S. is outperforming the rest of the world, said Bill Nichols, head of U.S. equities at Cantor Fitzgerald. But have stocks run too far too fast? Even with good fundamentals and better economic data and stronger earnings. is it time for a pause?

While the Fed is expected to increase rates next year, Ed Hyland, a global investment specialist for J.P. Morgan Private Bank, said a slow-and-steady approach to raising rates shouldn’t diminish the appeal for U.S. stocks.

It’s fundamentally good because it means that the Fed is removing this extraordinary easing, and they’re only doing that because they feel that the economy is able to generate self-sustaining growth, he said.

Stock markets were closed Wednesday in some countries, including Germany and Japan. The Stoxx Europe 600 index gained 0.4%. Despite the continent’s troubles, the pan-European index eked out a gain for the year of 4.4%.

In Asia, the Shanghai Composite Index rose 2.2% and notched a yearly gain of 53%. Hong Kong’s Hang Seng Index rose 0.4% and gained 1.3% for the year.

In commodity markets, crude-oil futures posted a fresh five-year low, shedding 1.6% to $53.27 a barrel.

Gold futures lost 1.4% to $1183.90 an ounce, ending the year with a fall of 1.5%.

In corporate news, China’s Fosun International has agreed to buy Meadowbrook Insurance Group for about $433 million. The offer price of $8.65 a share represents a 21% premium over Meadowbrook’s closing price of $7.13 on Tuesday. Meadowbrook shares jumped 19%.

Shares of American Eagle Energy Corp. fell 2.2% after announcing Wednesday that it suspended drilling operations and likely won’t resume until oil prices improve. The company is the latest to suffer from the sustained decline in oil prices.

NephroGenex Inc. shares soared more than 200% after announcing positive safety study results for its diabetic nephropathy treatment Pyridorin.

Write to Dan Strumpf at daniel.strumpf@wsj.com

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