By Chuck Mikolajczak
NEW YORK (Reuters) - Biotech stocks tumbled on Monday, dampening an early rally on Wall Street, after leading U.S. Democratic presidential candidate Hillary Clinton tweeted her intent to tackle unnecessarily high prices in some drug markets.
"Price gouging like this in the specialty drug market is outrageous. Tomorrow I'll lay out a plan to take it on," she tweeted, citing a New York Times article about rapidly rising drug prices.
In the moments following Clinton's tweet at 10:56 a.m. EDT (1456 GMT), shares of many biotech companies turned down sharply.
The Nasdaq biotech index <.NBI>, which had been roughly unchanged on Monday morning, dropped 1 percent in the next half hour, dropping to a session low of 3,535.86 at 1:01 p.m. in New York, just over two hours after Clinton’s post on social network Twitter.
Heading into the last hour of trading, that index was down 4.6 percent, at 3,561.84. In the Nasdaq Composite index <.IXIC>, 25 of the largest point decliners were from the healthcare sector.
(GRAPHIC-Biotech shares tumble after Clinton tweet http://reut.rs/1FpRAcW)
Clinton was referring to an article about skyrocketing drug prices, in part caused by pharmaceutical companies adopting a strategy of buying older drugs and turning them into expensive specialty drugs.
Biotechs have been among the better performing stocks, having risen for seven straight years, including a gain of 12 percent for 2015.
They are also extremely volatile, subject to wild swings over shorter time frames and are among the more expensive stocks. The trailing price-to-earnings ratio for the Nasdaq biotech index stands at 28.2, according to Thomson Reuters data, versus 18.37 for the broader S&P 500.
"The one issue overhanging healthcare, the one 'black swan' event on healthcare in general, is real, true drug price controls like you have in Canada, France and the UK," said Sven Borho, founding general partner and fund manager at Orbimed Advisors LLC, in New York.
"Especially when you have headlines like you have today, without a lot of meat on it, then the fantasy goes wild."
After climbing more than 1 percent in the early portion of trading, Wall Street sharply pared gains due to the biotech weakness, with both the Nasdaq and S&P 500 <.SPX> falling to session lows before rebounding modestly.
The Proshares UltraShort Nasdaq biotech ETF <BIS.O>, which seeks daily investment results of two times the inverse of the Nasdaq biotech index, hit a session high of $31.68 and was last up 9.2 percent at $31.21.
(Reporting by Chuck Mikolajczak; Editing by Bill Rigby and Andrew Hay)