Biggest sports business stories of 2015

From "Deflategate" to horse racing's first Triple Crown in 37 years, sports generated some of the most memorable story lines of 2015.

For every big sports moment this year, someone was making or losing cash.

We took a look at some of the key events in the sports business for 2015.

— By CNBC's Jacob Pramuk
Posted Dec. 30, 2015

Daily fantasy sports companies FanDuel and DraftKings burst into the public consciousness this year. Both finished funding rounds of more than $200 million over the summer and launched ad barrages at the start of the National Football League season.

But the companies faced considerable scrutiny by October. First came unfounded suspicion that a DraftKings employee may have used confidential information to win money in a FanDuel contest.

Attorneys general in states including New York and Illinois have since ruled daily fantasy sports illegal gambling under state laws. FanDuel and DraftKings are now embroiled in legal battles to operate in both states. (CNBC parent Comcast and NBC Sports are investors in FanDuel.)

American Pharoah enjoyed one of the best years in horse racing history while generating a big haul for his owners.

Pharoah won the coveted Triple Crown, becoming the first horse to do so in 37 years. For the year, he raked in $8.2 million in prize winnings for his owners, the Zayat family.

The horse will start breeding in February, and stud fees could reach between $200,000 and $250,000 per stud. The Zayats sold his breeding rights earlier this year for an undisclosed sum.

The widely anticipated May bout between Floyd Mayweather and Manny Pacquiao may have underwhelmed many viewers. But it marked a windfall for the boxers, promoters and television companies involved.

The fight generated more than $400 million in domestic pay-per-view revenue, according to Showtime and HBO, which sold showings. No other fight had topped $150 million in U.S. pay-per-view sales.

The networks added that total worldwide revenue is estimated at more than $500 million, including ticket sales at the MGM Grand in Las Vegas, distribution and sponsorship. MGM also saw a big boost in activity at its casinos.

The NFL took in at least $7 billion in revenue last season, and quite possibly more, according to multiple reports. Despite lingering concerns about the league this year, nothing yet indicates that its sales numbers will stop growing.

But the league faces challenges. A potential $1 billion health settlement with former players remains under appeal, as many ex-players have objected to its scope in taking care of players who suffered from severe head trauma. While the NFL has attempted to reduce concussions and invested in better technology and treatment, questions remain about how to make the game safer for players.

This year also saw the Super Bowl champion New England Patriots suspected of intentionally underinflating balls in a January playoff win. Quarterback Tom Brady was suspended four games after results of a probe were released, but the ban was later reversed.

The incident became known as "Deflategate."

Serena Williams dominated women's tennis this year, compiling a 53-3 record in singles. The 34-year-old won three of four Grand Slam titles, bringing her career total to 21.

Williams racked up about $10.5 million in winnings for the year, better than any male or female player other than Novak Djokovic, who won more than $21 million. The run brought Williams' career prize money to nearly $75 million.

When protests surfaced in response to perceived racial tension and inequality at the University of Missouri, the school's football team joined in. At least 30 black Missouri players in November said they would not participate in team activities until the university system's president, Tim Wolfe, resigned.

Wolfe and another key administrator eventually stepped down, and the football team's action likely contributed to those resignations. Failing to field a football team could have cost the university an estimated $3 million or more per home game.

The program, part of the powerful Southeastern Conference, could take in an estimated $36 million this season.

The United States won the Women's World Cup in July, drawing 25.4 million viewers in its final victory over Japan. It was the most-watched soccer match in U.S. history.

Despite the attention, U.S. women's soccer players still lag far behind their male counterparts in salary and endorsement opportunities due to generally lower consumer interest in watching or attending games.

Each of the nine teams in the fledgling National Women's Soccer League — which started in 2013 after two previous U.S. women's leagues folded — has a $265,000 salary cap. Currently, franchises have to pay their players a minimum of $6,842 per year, with a ceiling of $37,800.

Under Armour in January signed golfer Jordan Spieth to a new 10-year endorsement deal, the terms of which were not disclosed. He proceeded to finish fourth or better in golf's four major championships, winning two of them.

The sports apparel maker also signed a sponsorship extension with National Basketball Association Most Valuable Player Stephen Curry this summer, effectively for the rest of his career. Not to be outdone, rival Nike inked an unprecedented lifetime deal with superstar LeBron James this month.

Endorsement deals aside, the companies' stocks have enjoyed a strong run in 2015. Nike has led the Dow Jones industrial average with gains of 33 percent, while Under Armour has climbed 20 percent.