The S&P 500 (SNPINDEX:^GSPC) rocketed forward to huge gains in 2013, posting a total return of more than 32% for the year. But when you dig more deeply into the S&P's best sectors in 2013, you find that a few areas of the market really stood out from the pack. Let's take a look at the top three performers among S&P sectors last year and why investors in consumer discretionary, health-care, and industrial stocks outpaced the S&P 500's results in 2013.

For consumer discretionary stocks, improving economic conditions led to greater spending in a number of different areas that contributed to the sector's 43% gains. General Motors (NYSE:GM) continued its run of impressive performance in 2013, rising 42% for the second year in a row as auto sales figures kept rebounding. Similarly, Home Depot (NYSE:HD) rode the recovery in the housing market to more strong gains, with the home-improvement retailer's stock climbing 36% as homeowners became more willing to spend on improvements and renovation projects.

Meanwhile, health-care stocks jumped 41%, with biotech companies providing a big portion of the gains in the sector. Even though Gilead Sciences (NASDAQ:GILD) and Celgene don't carry as much weight in the sector as pharmaceutical giants like Johnson & Johnson and Pfizer, their higher growth potential drove investor interest in the sector. In particular, the recent FDA approval of Gilead's Sovaldi could revolutionize hepatitis C treatment, with its being the first oral therapy for certain genotypes of the disease that doesn't involve interferon. Across the sector, new therapies for various diseases are transforming the way patients get treatment, and companies like Gilead are making the most of the opportunity.

Finally, industrials jumped more than 40% in 2013, showing signs of a cyclical recovery in industrial and manufacturing activity. Among the best-known stocks, Boeing (NYSE:BA) was a high-flyer in industrials, as the aerospace industry has seen demand for new aircraft soar in recent years. Boeing's experience in seeing its airline customers ramp up their orders points to a greater willingness generally in companies to invest in their own futures, and industrial stocks are well positioned to benefit from greater demand throughout the sector.

Just because these sectors were strong in 2013 doesn't necessarily mean they'll keep outperforming this year. But with many of the same trends continuing in 2014, it pays to look out for companies in these sectors to see if they have the staying power to keep delivering solid returns this year and well into the future.