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) 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) 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) 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). 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).

Do You Know the Answer?

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

Feeling Lucky?

And finally, try picking a random portfolio suited to do-it-yourselfers with more detailed analysis at I'm Feeling Lucky.

Stockpickr is a wholly owned subsidiary of TheStreet.com.

More from Investing

General Electric's Stock Price Is at a Crossroads

General Electric's Stock Price Is at a Crossroads

Adobe-Magento Deal Highlights Escalating Cloud Wars

Adobe-Magento Deal Highlights Escalating Cloud Wars

Did Trump Just Torpedo the Stock Market Again?

Did Trump Just Torpedo the Stock Market Again?

10 Questions for PayPal Ahead of Its Big Investor Day

10 Questions for PayPal Ahead of Its Big Investor Day

Lowe's Q1 Miss Emerges as Home Depot Veteran Arrives

Lowe's Q1 Miss Emerges as Home Depot Veteran Arrives