U.S. stocks turned lower on Monday, led by declines from technology and consumer-discretionary companies as oil prices remained near $105-a-barrel amid ongoing political tensions in Libya

The S&P 500 Index declined 12.33 points, or 0.96 percent, to trade at 1,308.51 at 9:40 a.m. EDT. The Dow Jones Industrial Average declined 84.12 points, or 0.69 percent, to trade at 12,085.76. The Nasdaq Composite Index dipped 1.77 percent.

Fears of a civil war and a humanitarian crisis grew in Libya as forces loyal to Muammar Gaddafi escalated attacks on rebel-held cities in a bid to recapture control, causing dozens of deaths and mass exodus of people.

Crude oil futures in New York climbed by more than 1.06 percent to almost $105.53 a barrel. Oil prices have surged more than 23 percent since unrest erupted in northern Africa and the Middle East earlier this year.

Intel Corp. (NASDAQ:INTC) declined 2.04 percent after the company stock was downgraded to “market weight” rating from “overweight” rating at Wells Fargo & Co. Cisco Systems Inc. (NASDAQ:CSCO) shares declined 1.68 percent to $18.09.

CIENA Corp. (NASDAQ:CIEN) stock plunged 10.38 percent as it guided second quarter revenue below Street view. The company expects second quarter revenue of $415 million to $435 million, below Street view of $438.54 million. The company projects second quarter adjusted gross margin to be in the low 40s range.

Shares of JDS Uniphase Corp. (NASDAQ:JDSU) slumped 6.4 percent and Micron Technology Inc. (NASDAQ:MU) declined 5.8 percent.

Shares of TomoTherapy Inc. (NASDAQ:TOMO) jumped 25.07 percent after Accuray Inc. (NASDAQ:ARAY) said it has agreed to buy TomoTherapy for $277 million or $4.80 a share in cash and stock, paving the way for the creation of a premier radiation oncology company.

Western Digital Corp. (NYSE:WDC) climbed 14.76 percent after the company said it agreed to acquire Hitachi Global Storage Technologies, a wholly owned subsidiary of Japan’s Hitachi , for $4.3 billion in cash and stock.

The euro declined 0.06 percent to 1.3978 against the dollar while the greenback declined 0.22 percent against the yen.