The S&P 500 climbed nearly 1% last week to 1,149.99, driven mostly by company-specific news.

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

American International Group (NYSE: AIG)

21.9%

Citigroup (NYSE: C)

13.4%

Zions Bancorp.

12%

Huntington Bancshares (Nasdaq: HBAN)

10.3%

MEMC Electronic Materials

10%

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

Losers on the week:

Company

Percentage Loss on the Week

CF Industries Holdings (NYSE: CF)

(7.6%)

EQT Corp (NYSE: EQT)

(7.2%)

AK Steel Holding (NYSE: AKS)

(6.6%)

Archer-Daniels-Midland (NYSE: ADM)

(6.4%)

Pall Corp.

(5.9%)

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

Lower quality names led last week
Government-subsidized companies led market gains last week on hopes they will disentangle their operations from the government soon. Citigroup was a major winner after an offering of its trust preferred securities was well received.

Citigroup was also the most actively traded stock last week. Investors big and small have been piling into the battered bank, and last week momentum picked up after positive comments from the company's CEO Vikram Pandit. Pandit said the bank is on a sustainable path to profitability and forecasts the bank's return on assets for its core business will grow this year. He also reiterated the government's plans to sell its stake in Citi some time this year. His comments come after the bank has been shedding assets. Analysts are growing more bullish on the company's outlook as hopes permeate that the worst is behind the bank.

AIG, another heavily government subsidized entity, has been divesting assets to shore up its financial position and get from out from underneath the government's web as well. Last week the insurance company was able to sell another of its foreign life insurance businesses, Alico, to MetLife for $15.5 billion. This is the company's second divestiture this year after selling its Asian life insurance business to Prudential for $35.5 billion. These actions help the company in pay down its remaining $129.3 billion debt to the government (the amount on record AIG owes as of the fourth quarter), but there's still a ways to go.

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:

Fool contributor Jennifer Schonberger does not own shares of any of the companies mentioned in this article. You can follow her on Twitter. The Motley Fool has a disclosure policy.