The S&P 500 delivered one of its best years in recent history in 2021, gaining more than 27 peercent. Most U.S. investors had a lot of winners in their portfolios this year, but some stocks certainly performed better than others. Here’s a look at the 10 best-performing stocks in the entire S&P 500 in 2021. 1. Devon Energy The energy sector came roaring back in 2021, and crude oil and natural gas prices both hit multi-year highs. There were plenty of big oil and gas winners in 2021, but Devon Energy was the best performer in the entire S&P 500, gaining 193.9 percent on the year. 2. Marathon Oil Oil and gas is a recurring theme among the S&P 500 top performers of 2021, and Marathon Oil gained 145.1 percent on the year. 3. Fortinet Outside of the energy sector, cybersecurity leader Fortinet was the best tech stock of 2021, …