For the second year in a row, the most valuable professional sports team is the Dallas Cowboys, with a market value of more than $4 billion. The list of the top 10 sports franchises with the highest market value in 2017 is based on Forbes annual ranking of National Football League, National Hockey League, National Basketball Association, Major League Baseball, Formula 1, soccer and Nascar teams. This year, the list is dominated by football and soccer teams. Only two NBA teams are in the ranking, while only one MLB team is in the top 10. No NHL, Formula 1 or Nascar teams made this list.

1. Dallas Cowboys

With a market value of $4.2 billion, the world's most valuable sports team in 2017 is the Dallas Cowboys. Although the team has not won an NFL championship in more than 20 years, it is the most valuable team in sports, largely due to its $1.2 billion home stadium, constructed in 2009. In 2013, the Dallas Cowboys sold the naming rights of the stadium to AT&T Inc. (NYSE: T) for an estimated $400 million to $600 million. Cowboys owner and general manager Jerry Jones, who purchased the team in 1989 for $150 million, is worth an estimated $5.6 billion. (For more, see Building a Fortune: Jerry Jones and the Cowboys.)

2. New York Yankees

For the second year in the row, the New York Yankees is the only Major League Baseball team featured in the top 10 most valuable sports teams. With an estimated value of $3.7 billion, the Yankees moved from the No. 4 spot last year to the No. 2 spot this year. The team's most recent championship was in 2009, but it has 27 World Series titles, more than any other MLB team. According to Forbes, the Yankees also lead the sport in sponsorship revenue ($120 million) and premium seating revenue ($130 million). The Yankees' overall market value increased 9% from 2016.

3. Manchester United

Manchester United plc (NYSE: MANU), the only publicly traded sports team on the list, had the most valuable sports team in 2011 and 2012. This year, however, the team is in third place, with a market value of $3.69 billion, up 11% from 2016. Soccer's richest team is a master at generating commercial income. For example, it entered a decade-long kit manufacturer/sponsorship deal worth almost $1 billion with Adidas, beginning in the 2015-2016 season.

4. FC Barcelona

FC Barcelona's market value of $3.64 billion, up 2% from last year, makes the organization the second most valuable soccer team in 2017. Led by Lionel Messi, the world's second highest paid soccer player, FC Barcelona signed a kit deal with Nike Inc. (NYSE: NKE) that is estimated to be worth around $175 million per year and will run through the 2027-2028 season. In addition, the team is slated for a $650 million stadium renovation in which additional ticket revenue is anticipated, as the stadium's seating capacity will expand to 105,000.

5. Real Madrid

Real Madrid's net worth declined 2% from last year. Its 2017 market value of $3.58 billion means it falls from the most valuable soccer team (and second most valuable sports team overall) in 2016 to the third most valuable soccer team this year. Despite the dip in ranking, the Spanish soccer team won the UEFA Champions League in the 2015-2016 season and is led by soccer's highest paid athlete, Cristiano Ronaldo. Real Madrid was the most valuable team in professional sports in 2013-2015.

6. New England Patriots

The team with the second highest market value in the National Football League is the New England Patriots. As of 2017, its market value is estimated at $3.4 billion, up 6% from 2016. The Patriot's loyal fan base allow for unique revenue opportunities for the franchise. In 2015, the Patriots unveiled the Optum Field Lounge at the south end zone of Gillette Stadium. This members-only club carries an annual fee of $1,500, mandates that a minimum of two memberships be purchased at a time, and does not include the cost of season tickets.

7. New York Knicks

For the second year in a row, the National Basketball Association's most valuable team is the New York Knicks. The team's estimated value is $3.3 billion, up 10% from 2016. The New York Knicks took the title of most valuable NBA franchise from the Los Angeles Lakers in 2016, largely due to a new 20-year media rights deal worth $100 million in the first year. The Knicks' lofty valuation takes into account the team's access to its own television network and landmark arena, by virtue of being a part of the Madison Square Garden Co. (NYSE: MSG) enterprise.

8. New York Giants

Another NFC East football team ranks as one of the most valuable sports team in 2017. The New York Giants, the third most valuable NFL team, has an estimated value of $3.1 billion, up 11% from 2016. A large part of this valuation is due to strong revenue performance by the franchise. According to GOBankingRates, the New York Giants earned an average of $30 more per ticket sold compared to the average cost of an NFL ticket. In 2016, an average NFL ticket was $92.98, while the Giants charged $123.40.

8. San Francisco 49ers (Tie)

The San Francisco 49ers made the cut with a market value of $3 billion, bumping the Washington Redskins out of the top 10. The 49ers' valuation increased 11% this year, making it the fourth most valuable football team in 2017. The team has struggled on the field, though, with a record of 2-14 last season. Yet, the average ticket price of $117 was $24 above the average NFL ticket. The team may have a hard time making it onto this list next year, as its move to Santa Clara's Levi's Stadium in 2014 has not been well received and ticket sales are on the decline.

9. Los Angeles Lakers (Tie)

The second most valuable team in the NBA is the Los Angeles Lakers. The organization is worth an estimated $3 billion, up 11% from last year. In 2012, the Lakers began a 20-year, $4 billion local television deal with Time Warner. The team has won a staggering 16 championships with the help of household names like Shaquille O'Neal, Kobe Bryant, Magic Johnson and Kareem Abdul-Jabbar.  

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