Waltham, Mass.-based contract research organization Parexel reduced its 2009 fiscal year guidance, and share prices plunged more than 40% to $8.05 in late morning trading.

Citing slower than expected sales in September and a negative impact from foreign exchange rates, the company lowered its full-year consolidated revenue guidance to $1.1 to $1.3 billion, down from $1.22 to $1.25.

“We anticipated a slowdown during the summer months, and then expected an acceleration of activity in September as has been typical in the past. Ultimately, however, sales performance for the quarter turned out to be short of target,” said Parexel chairman and CEO Josef H. von Rickenbach in a company statement.

Parexel reported service revenues of $263 million for the first quarter of fiscal year 2009, a 26.4% increase compared with the same period prior year, but net income for the quarter was down to $13.6 million from $13.9 million.