The S&P 500's Biggest Movers

The S&P 500 broke a six-day winning streak last week, ending the week down 0.8% to 1,136.03 as earnings season kicked into gear. Disappointing results from Alcoa and uneasy comments from JPMorgan weighed on the market.

Pops and drops
Here are last week's five biggest S&P 500 upticks and drops (measured Friday close to Friday close).

Winners on the week:

Source: Capital IQ (a division of Standard & Poor's).

Losers on the week:

Source: Capital IQ (a division of Standard & Poor's).

A closer look
Shares of SUPERVALU got a boost last week after the grocer swung to a surprise profit in its fiscal third quarter, thanks to cost controls. Though the company was able to turn a profit, sales continued to wane as shoppers limited their spending to necessities. Total sales slid 9% in the quarter, while same-store sales (a key measure of financial health for retailers) slipped 6.5%. The company maintained its earnings guidance for the year, but lowered its same-store sales projections.

On the flip side, shares of MetroPCS Communications continued to take it on the chin. This is the second week in a row that the company has made the S&P 500's biggest losers list. Investors are concerned that the small wireless carrier's margins will suffer as it tries to keep up with ongoing price competition. While MetroPCS added customers in the fourth quarter, it said the percentage of subscribers that fled its service increased to 5.3% in the quarter, from 5.1% a year ago. What's more, company executives unveiled plans to help MetroPCS compete, including being a low-price leader. However, they warned that the move could hinder profits.

Interested in the other stocks on this list? Visit The Motley Fool's free CAPS community for further research and opinions on these stocks!

Related Foolishness:

• A Fool's Look Back
• The Fool Looks Ahead
• 7 Reasons to Worry About Next Week