Editor's Note: In this feature from Stockpickr, we highlight lists of stocks that have made new highs, lows or seen other unusual activity.

52-Week Highs

: Credit card company

MasterCard

(MA) - Get Report

hit a 52-week high for the second straight session, gaining another 4.3% after announcing on Friday its plans to convert Class B shares into Class A on an accelerated basis. The company gained $6.84 to $164.49.

Biggest % Gainers

:

Harvest Natural Resources

(HNR)

jumped 37% after Venezuela's National Assembly approved a change in operations under which the country would take a controlling stake. The stock gained $3.68 to $13.50.

Rising on Unusual Volume

: Diversified investments firm

Life Partners

(LPHI) - Get Report

surged 7% Monday as shares traded at five times average volume. The Waco, Texas company added $2.07, closing at $32.18.

52-Week Lows

:

American Commercial Lines

( ACLI) fell down to a 52-week low Monday after the company lowered guidance. On the news, the shipping company's shares dropped $2.78, or 10%, to $24.35.

Biggest % Losers

:

Encysive

( ENCY) plummeted 44% Monday after the Food and Drug Administration rejected the company's pulmonary arterial hypertension treatment, Thelin. Shares fell $1.78, landing at $2.32.

Stocks with Unusual Option Activity

:

Orbcomm

(ORBC) - Get Report

was experiencing unusual option activity on Monday. Shares lost 11 cents, or 0.7%, to close at $16.09.

Latest Activist Situations

: Two hedge fund heavyweights, SAC Capital and Citadel, bought up shares of biotech company

BioMarin Pharmaceutical

(BMRN) - Get Report

. Monday, SAC Capital disclosed it owns a 5.1% "passive" stake in the company, and Citadel disclosed a 5.5% "passive" stake in the company. The company's shares gained 23 cents, or 1.3%, closing at $18.01.

Forum of the Day

gmartin1

charts Pfizer

(PFE) - Get Report

.

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Cade Gatlin asks,

How do you tell if a stock is "extended" and is likely nearing a pull-back?

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