Investors who owned stocks in the 2010s generally experienced some big gains. In fact, the SPDR S&P 500 (NYSE: SPY) total return for the decade was 250.5%. But there’s no question some big-name stocks did much better than others along the way.Southwest’s Difficult DecadeOne underperformer of the last decade was U.S. airline Southwest Airlines Co (NYSE: LUV).The big news of the past decade for Southwest was its $3.2 billion acquisition of AirTran Airways. The merger was announced in September 2010 and added 25 additional destinations to Southwest’s routes, including AirTran hub Atlanta, Georgia.The deal was ultimately approved by shareholders and regulators, and Southwest closed the deal on May 2, 2011.Southwest shares started the 2010s trading at around $11.18 but hit their decade low of $6.65 by late 2011. Southwest shares went on a tear in 2013 and 2014, eventually peaking at $48.99 in late 2015.The rally resumed in late 2016 when Warren Buffett’s Berkshire Hathaway Inc. (NYSE: BRK-A) (NYSE: BRK-B) took a new stake in Southwest. That momentum ultimately pushed the stock to its all-time high of $65.12 at the very end of 2017.2020 And BeyondFrom early 2017 to early 2020, Southwest shares traded mostly sideways in a range between $45 and $65 before the bottom fell out during the COVID-19 outbreak. In March, Southwest traded to a more than five-year low of $22.47 before bouncing back to around $34 today.Despite the bid 2020 hit, investors have still made decent returns in the popular airline stock over the past decade. In fact, $1,000 worth of Southwest stock in 2010 would be worth $2,940 today, assuming reinvested dividends.Looking ahead, analysts expect even more gains for Southwest in 2020. The average price target among the 17 analysts covering the stock is $38, suggesting 11.4% upside from current levels.Related Links:Here’s How Much Investing ,000 In Royal Caribbean Stock Back In 2010 Would Be Worth TodayHere’s How Much Investing 0 In Carnival Stock Back In 2010 Would Be Worth TodaySee more from Benzinga * Airline Stock Short Sellers Have Made A B Profit In 2020 * How Large Option Traders Are Playing Airlines Right Now * Delta, United Extend Loyalty Memberships For Another Year As Coronavirus Pummels Airlines(C) 2020 Benzinga.com. Benzinga does not provide investment advice. All rights reserved.