The S&P 500 gained 0.9% last week to 1,159.90, its third consecutive week of gains. The market rose on encouraging economic data and with the Federal Reserve deciding to keep rates on hold at historic lows, underscoring continued low borrowing costs that help fuel the recovery.

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

Winners:

Company

Percent Gain

LSI (NYSE: LSI)

15.1%

GameStop (NYSE: GME)

9.9%

Coventry Health Care (NYSE: CVH)

8.3%

Aetna (NYSE: AET)

8.2%

First Horizon National

7.8%

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

Losers:

Company

Percent Loss

Consol Energy (NYSE: CNX)

(16.2%)

Nabors Industries

(11.7%)

Southwestern Energy

(10.7%)

Cabot Oil & Gas

(8.9%)

Devon Energy (NYSE: DVN)

(8.8%)

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

A closer look
Shares of LSI got a boost last week after the company raised its first-quarter revenue and earnings outlook on a pickup in business spending on technology. LSI also said it is repurchasing $250 million in shares, and that it would not rule out other stock repurchases.

GameStop also issued upbeat guidance for 2010, which overshadowed a disappointing fourth quarter. Shares leapt on the news, but perhaps investors should be cautious. My Foolish colleague Rick Aristotle Munarriz is skeptical of the company's forecast, given management's track record of inaccurate calls.

In a move to broaden its natural gas business and diversify its risk profile, Consol Energy said it is buying Dominion Resources' (NYSE: D) Appalachian exploration and production business for $3.5 billion. However, shares slipped last week after the coal and natural gas company said it would issue $4 billion in debt and equity to finance the purchase and develop the property. My Foolish colleague Toby Shute writes that shareholders should focus on the company's move to position itself for the long term, when natural gas could become a more desirable energy choice if the government puts more environmental restrictions on the use of fuel sources.

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

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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. Coventry Health Care is a Motley Fool Stock Advisor selection. Motley Fool Options has recommended a write covered calls position on GameStop. The Fool has a disclosure policy.