7. John Paulson (Paulson & Co.)
Net gains in 2015: -$2.1 billion
Net gains since inception: $21.4 billion (1994)
Fund's assets under management: $15.6 billion
Paulson's net worth: $11.4 billion
Highlights: In 2015, John Paulson fell from the No. 3 spot on the list to No. 7. He became famous for his 2007 bet against subprime housing; it made him and his investors billions. Since then his returns have been volatile, and his fund's assets have dropped from a peak of $38 billion in 2011 to about $15.6 billion. Just last month Paulson pledged his personal wealth as collateral for a line of credit for his fund from HSBC USA.
6. Stephen Mandel (Lone Pine Capital)
Net gains in 2015: $1.2 billion
Net gains since inception: $22.4 billion (1996)
Fund's assets under management: $29.5 billion
Mandel's net worth: $2.4 billion
Highlights: Lone Pine Capital is led by the billionaire Steve Mandel, who worked at legendary hedge fund Tiger Management early in his career. The fund is now part of a group of funds launched by Tiger alumni known as "Tiger Cubs."
Mandel is betting on companies that dominate the web in 2016, according to an investor letter.
Lone Pine's Cascade fund, its long-only fund, rose 1.4% in the fourth quarter to end 2015 down 1.2%. Meanwhile, Lone Pine's Cyprus fund rose 4.6% in the fourth quarter, ending the year up 8.7%, while its Kauri fund rose 4.4% in the quarter to end 2015 up 8.9%.
As of the end of 2015, the Cascade fund's 10 largest long-stock positions were Microsoft, Amazon, Tencent Holding, Facebook, Visa, Dollar Tree Stores, Williams Companies, FleetCor Technologies, JD.com, and Charter Communications. The fund trimmed some of its stake in embattled Canadian drug company Valeant Pharmaceuticals.
5. Andreas Halvorsen (Viking)
Net gains in 2015: $1.7 billion
Net gains since inception: $22.5 billion (1999)
Fund's assets under management: $30.2 billion
Halvorsen's net worth: $2.8 billion
Highlights: Viking, which like Lone Pine is a "Tiger cub" hedge fund, had a strong 2015 overall, finishing up 8.3% for the year, according to the fund's fourth-quarter letter. The hedge fund bought more Valeant Pharmaceuticals stock in the fourth quarter, even after it dragged down the fund's performance and was its "biggest loser."
4. Seth Klarman (The Baupost Group)
Net gains in 2015: -$800 million
Net gains since inception: $22.6 billion (1983)
Fund's assets under management: $27 billion
Klarman's net worth: $1.38 billion
Highlights: In 2015, The Baupost Group had its third losing year in its 33-year history. Klarman described it as a year of "dodging relentlessly falling knives."
The fund's public-investments portfolio fell 6.7% in 2015, while the fund's private investments gained 2.4%, according to a separate investor update seen by Business Insider. The fund's public-investment returns were largely dragged down by Cheniere Energy, Micron Technology, Keryx Biopharmaceuticals, and Antero Resources.
3. David Tepper (Appaloosa)
Net gains in 2015: $1 billion
Net gains since inception: $22.8 billion (1993)
Fund's assets under management: $17.9 billion
Tepper's net worth: $11.6 billion
Highlights: Lately, Tepper has been going after embattled solar-energy company SunEdison, the parent company of one of his holdings. He's taken a stake in TerraForm Power, one SunEdison's yieldcos.
2. George Soros (Quantum Endowment Fund)
Net gains in 2015: $900 million
Net gains since inception: $42.8 billion (1973)
Fund's assets under management: $29 billion (family office)
Soros' net worth: $24.5 billion
Highlights: Quantum Endowment Fund, a family-office hedge fund, dropped from the No. 1 spot on last year's list to No. 2. Quantum, which had been led in recent years by Soros' protégé Scott Bessent, made $900,000,000 in net gains for 2015, the report said.
Bessent just started his own hedge fund, Key Square Group, this month and will be managing nearly $4.5 billion in assets, making it one of the largest launches of all time.
Soros has retired from the day-to-day operations of his fund, and is now focused on his foundations and philanthropy. At the World Economic forum in Davos this month, he sounded really bearish, saying that the next crisis will stem from China and the deflationary forces it's transmitting to the rest of the world.
1. Ray Dalio (Bridgewater Pure Alpha)
Net gains in 2015: $3.3 billion
Net gains since inception: $45 billion (1975)
Fund's assets under management: $82.3 billion
Dalio's net worth: $15.6 billion
Highlights: Dalio's Bridgewater Associates is the largest hedge fund in the world with approximately $160 billion under management. At the World Economic Forum in Davos this month, Dalio told Business Insider executive editor Jay Yarow that he's worried about growth in the global economy because there's no country acting as a "locomotive" right now.