Biotechnology has surged higher in recent months as a combination of good news and speculation lifted the group's well-knowns and unknowns alike, but on a day that sellers took control of the broad market, this superheated sector also took a tumble.

Two broad sector measures reflected the selloff. The Amex Biotech Index ended the day down 4.6%, and the Nasdaq Biotech Index gave up 6.1%.

Individual stocks were hit hard, and one of those feeling the pain most acutely was

Protein Design Labs

(PDLI) - Get PDL BioPharma, Inc. Report

, which fell nearly 11% to $15.35.

Human Genome Sciences

(HGSI)

dropped almost 8% to $12.40.

Vertex

(VRTX) - Get Vertex Pharmaceuticals Incorporated Report

lost 6% to $14.62.

Elsewhere in sector,

Genzyme

(GENZ)

fell 6% to $43.48,

Millennium

(MLNM)

shed almost 6% to $14.96, and

Chiron

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was down 5% to $44.75.

Most of the well-known names in the group were under some degree of selling pressure, including

Biogen

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, off 5% to $43.25, and

Amgen

(AMGN) - Get Amgen Inc. Report

, lower by 3% to $63.82.

Genentech

(DNA)

held up relatively well, declining only 0.6%, or 46 cents, to $74.07. Helping support Genentech was

a bullish report from research firm UBS on the stock and the company's prospective cancer treatment Avastin.

Gilead

(GILD) - Get Gilead Sciences, Inc. (GILD) Report

was off 5% to $51.30, and

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MedImmune

(MEDI)

declined 1% to $35.76.

(Adam Feuerstein, a columnist for

TheStreet.com's

sister site

RealMoney.com

,

took a look today at the biotech sector's recent run-up, and he offered some insight regarding just how long the optimism might continue lifting these stocks.)

The smaller-cap names were also seeing their fair share of selling.

Oxigene

(OXGN)

was down 11% to $9.01.

Geron

(GERN) - Get Geron Corporation Report

lost more than 4% to $6.86, while

VaxGen

(VXGN)

slipped 2% to $5.06.

Large pharmaceutical companies headed lower, as well.

Novartis

(NVS) - Get Novartis AG Sponsored ADR Report

was down 0.6% to $41.60,

Pfizer

(PFE) - Get Pfizer Inc. Report

dropped 1.3% to $35.60, and

Merck

(MRK) - Get Merck & Co., Inc. (MRK) Report

lost 1.5% to $62.30. Meanwhile,

GlaxoSmithKline

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fell 3% to $41.70.

Forest Laboratories

(FRX)

was sent down 12% to $53.29 after the company reported

disappointing data from a recent study involving the company's Alzheimer's treatment. The Amex Pharmaceutical Index declined 2% on the day.