UPDATE 1-Ackman's Pershing Square ends 2015 with 20.5 pct drop

(Adds details on other funds' returns, quote)
By Svea Herbst-Bayliss
BOSTON, Jan 5 (Reuters) - Billionaire investor William
Ackman's Pershing Square (N:SQ) Holdings hedge fund ended 2015 with a
20.5 percent loss after Valeant Pharmaceuticals (N:VRX) VRX.TO , a top
holding, was battered in the second half of the year.
That put the closely watched activist investor into the same
league as rival billionaire hedge fund manager David Einhorn,
whose Greenlight Capital finished also ended the year with a 20
percent drop, according to investor updates seen by Reuters.
For Ackman, the drop marks the worst performance in his
firm's 11-year history. For Einhorn, it was the first down year
since his fund lost 23 percent in 2008, when many hedge funds
were in the red during the financial crisis.
Pershing Square Holdings, one of several portfolios run by
the Ackman's $14.9 billion hedge fund, ended December nearly
flat with a 0.3 percent gain for the month, the update showed.
Einhorn's roughly $11 billion fund posted a similar return,
inching up 0.4 percent in December, the update showed.
Pershing's loss had been expected since Ackman had been hurt
by accelerating falls in big name stocks since the summer
months. But it also illustrates just how volatile the activist
investor's returns can be after he scored a 40 percent gain in
2014 when he ranked among the industry's best performers.
Valeant hurt Pershing Square while Greenlight was hit by
bets on Consol Energy CNX.N and Micron Technology MU.O .
Barry Rosenstein's Jana Partners fund lost 5.4 percent last
year, falling on bets on semiconductor company Qualcomm QCOM.O
and car rental group Hertz Global HTZ.N .
Even though 2015 is expected to be remembered as another
disappointing year, some funds sidestepped disasters and
finished the year with sizable gains.
Computer model-driven firm Renaissance Technologies' $5.5
billion Institutional Diversified Alpha fund gained 16.2
percent, while the firm's Renaissance Institutional Equity Fund
finished the year with a 17.3 percent gain.
Jacob Gottlieb's Visium Asset Management's $2.5 billion
Visium Global fund ended up 10.3 percent.
Hedge funds have come under "scrutiny from investors, as
returns from the industry as a whole have simply not been on par
with expectations," wrote Stanley Altshuller, chief research
officer at investment services firm Novus Partners. "But the
averages hide many positive outlying managers who were able to
identify massive opportunities and deliver solid returns."