NEW YORK (TheStreet) -- Stocks extended deep losses on Friday afternoon as crude oil posteda big loss for the week.

The S&P 500 was down 1.2%, the Nasdaq slid 1.2%, and the Dow Jones Industrial Average fell 1%.

Oil prices continued to decline as West Texas Intermediate crude closes 0.6% lower to $48.14 a barrel and down 5.4% for the week. Prices dropped after the total number of active U.S. rigs drilling for oil climbed 21 to 659 over the week, according to Baker Hughes. Crude took a dive last week after six world powers agreed to a nuclear deal with Iran that would lead to Iranian oil on global markets.

Basic materials stocks were the worst performers on Friday. BHP Billiton (BHP), Rio Tinto (RIO), and Vale (VALE) dropped, while the Materials Select Sector SPDR ETF (XLB) fell 2.8%.

BlackBerry (BBRY) dropped nearly 4% after CEO John Chen said the results of a turnaround plan would likely be seen in the next 12 to 18 months. Chen had previously given the strategy a six-month timeline, which included a move to software and away from smartphones, for it to gain traction. 

Amazon (AMZN) was one of the few bright spots on markets Friday after blowing past quarterly estimates. The e-commerce giant earned 19 cents a share while analysts expected a loss of 14 cents. Sales climbed nearly 20% to $23.18 billion, ahead of estimates of $22.39 billion. The better-than-expected quarter was tied to strong sales in North America and growth in Prime subscriptions. Shares surged 10%.

Amazon's surge was countered by Biogen (BIIB) which sank 21% after lowering full-year guidance. The biopharmaceutical company anticipates 2015 revenue growth between 6% and 8%, down from previous growth estimates of 14% to 16%.

Anthem (ANTM) and Cigna (CI) slipped after announcing a merger deal Friday following a month of reports. Indianapolis-based Anthem will acquire health insurance company Cigna for $54.2 billion, a deal that values Cigna shares at $188 a share. Cigna and Anthem shares fell more than 2%.

In other earnings news, Starbucks (SBUX) earned 42 cents a share, a penny above estimates, while revenue climbed nearly 18% to $4.88 billion. Global traffic increased 7% compared to expectations of 6.2%. The stock rose more than 3%.

Visa (V) spiked 4.8% after beating analysts' estimates on the top- and bottom-lines. The credit card company earned 74 cents a share, beating expectations by 15 cents, while sales surged 11.4% to $3.52 billion. Payments volume increased 11% on a constant-dollar basis.

Xerox (XRX) climbed 1.8% after the printing company reported a mixed quarter. Earnings of 22 cents a share were in-line with expectations, while sales of $4.59 billion fell 7.1% from a year earlier and missed by $50 million.

American Airlines (AAL) reported record profit in its second quarter. Adjusted net income of $2.62 a share beat estimates by 2 cents. Total revenue passenger miles climbed 1.1% over the quarter.

AT&T (T) received final regulatory approval for its $48.5 billion acquisition of DirecTV (DTV), according to Reuters. The Federal Communications Commission likely will announce the results of their vote on Friday. AT&T and DirecTV shares were up more than 2%.

U.S. insurance company StanCorp Financial Group (SFG) shot nearly 50% higher on news Japanese firm Meiji Yasuda Life Insurance would acquire it for 600 billion yen ($4.8 billion).

Sales of single-family new homes in the U.S. fell 6.8% to an annual rate of 482,000 in June, its slowest pace in seven months. Economists had expected a reading of 550,000. New home sales in May were revised down to 517,000 from an original reading of 546,000.