The S&P 500 managed to rally 2.2% last week, to 1,135.68, after a strong move up early in the week on a $1 trillion European bailout plan.

Pops and drops
Here are the five biggest S&P 500 upticks and five biggest S&P 500 drops of last week (measured Friday close to Friday close):

Winners on the week:

Company

Percentage Gain on the Week

MetroPCS Communications (NYSE: PCS)

22.0%

Legg Mason (NYSE: LM)

20.8%

Quanta Services

14.0%

Sprint Nextel (NYSE: S)

13.5%

JDS Uniphase

13.2%

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

Losers on the week:

Company

Percentage Loss on the Week

Dean Foods (NYSE: DF)

(34.6%)

Moody's (NYSE: MCO)

(7.7%)

priceline.com

(7.6%)

Monsanto (NYSE: MON)

(7.6%)

NVIDIA (Nasdaq: NVDA)

(7.2%)

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

A closer look
Shares of Legg Mason got a boost after the investment management company posted fourth-quarter profit that beat analyst estimates, compared with a loss in the same period last year. The company also laid out its plans for structural changes, including cutting close to 10% of its workforce and moving back-office functions to affiliated investment firms. Legg Mason estimates the changes will save the company $130 million to $150 million per year by the fourth quarter of fiscal 2012. Legg Mason also said it will repurchase up to $1 billion in common stock.

On the downside, shares of Dean Foods took it on the chin after the food and beverage maker posted a 43% plunge in first-quarter net income due to price competition within its private-label milk business. The company also suspended its full-year earnings outlook.

Also on the downside, shares of Moody's got hit after the ratings agency revealed in its quarterly report that it had received a so-called Wells notice from the SEC, which is a letter the SEC sends firms when it's considering bringing charges against them. As my Foolish colleague Rich Duprey explained, the impact of the revelation of a Wells notice depends on how material the charges -- if any were to be brought -- would be for the business.

In Moody's case, the SEC alleges that the company's application to become a nationally recognized statistical rating organization contained "false and misleading" information. The agency contends the company failed to modify inflated ratings for European derivatives. Adding insult to injury, the Senate voted to create stricter regulations for credit rating agencies as part of a comprehensive bill on financial regulatory reform.

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Fool contributor Jennifer Schonberger does not own shares of any of the companies mentioned in this article. You can follow her on Twitter. Moody's, Monsanto, and Sprint Nextel are Motley Fool Inside Value recommendations. Moody's, NVIDIA, and priceline.com are Motley Fool Stock Advisor choices. Motley Fool Options has recommended a write puts position on Moody's and a synthetic long position on Monsanto. The Fool owns shares of Legg Mason and Quanta Services, and has a disclosure policy.