By Rex Crum, MarketWatch

SAN FRANCISCO (MarketWatch) -- Big declines from NetApp Inc. highlighted a swath of losses across the tech sector Thursday, sending nearly every major tech stock into the red and putting even more pressure on Hewlett-Packard Co. and its upcoming quarterly earnings report.

The losses helped drag down the Nasdaq Composite Index (RIXF) by 131 points, or 5.2%, to close at 2,380. The Philadelphia Semiconductor Index (SOX) and the Morgan Stanley High Tech 35 Index (MSH) each gave up about 6% on the day.

NetApp (NTAP) shares fell by $5.85, or 14%, to $35.80 after the data-storage technology company gave a disappointing quarterly report and outlook.

Brent Bracelin, who covers NetApp for Pacific Crest Securities, said that NetApp's warning just emphasizing a sense of negativity emerging over the data-storage and hardware sectors.

"Cautious commentary from Brocade, Dell and NetApp in the last week tied to unexpected slowdowns in July, which have extended into August, suggests fundamentals within IT hardware are eroding faster than we expected," Bracelin said, in a research note.

Late Wednesday, NetApp reported a fiscal first-quarter profit of $139.5 million, or 34 cents a share, compared with a profit of $150.7 million, or 40 cents a share, for the same period a year ago. Revenue rose to $1.46 billion from last year's sales of $1.15 billion.

Excluding one-time items, NetApp would have earned 55 cents a share, which met the forecast of analysts surveyed by FactSet Research, who also pegged NetApp's quarterly revenue at $1.5 billion.

Steve Gomo, NetApp's outgoing chief financial officer, said the company saw a "dramatic slowdown" in sales during July.

NetApp also gave a second-quarter forecast that fell short of analysts' estimates.

With NetApp in the lead, other data-storage company's shares also retreated.

NetApp's biggest rival, EMC Corp. (EMC), shed $1.92 a share, or 8.5%, to close at $20.59, hard disk-drive makers Seagate Technology (STX) fell 9.5% and Western Digital Corp. (WDC) was off by more than 7%.

Additionally, Brocade Communications Systems Inc. (BRCD) gave up 11%, JDS Uniphase Corp. (JDSUD) fell by 12.7%, Riverbed Technology Inc. (RVBD) shed more than 15% and electronics contract manufacturer Jabil Circuit Inc. (JBL) saw its shares fall by almost 12%.

Hewlett-Packard Co. (HPQ) fell $1.88 a share, or 6%, $29.51. The company confirmed it would acquire British software giant Autonomy Corp. for $42.11 a share. The deal represents a 64% premium over Autonomy's Wednesday closing share price.

Dell Inc. (DELL) gave up 44 cents a share, or 3% to fall to $13.76 after shedding 10% on Wednesday on reaction to the PC company cutting its full-year forecast.