Versar

Ticker: VSR

Friday's close: $4.50

Week's change: +18%

Versar's stock surged in a week when the company's protective suits gained approval for use by emergency workers in the event of a chemical or biological terrorism attack. The Springfield company, which specializes in homeland security and environmental safety services, makes suits that include coveralls, a chemical-splash hood, boots and a breathing system.

American Community Properties Trust

Ticker: APO

Friday's close: $11.30

Week's change: +7%

The real estate company's stock got a lift last week as it reported record first-quarter profit. The St. Charles company, which develops and manages real estate, earned $1.2 million (23 cents a share) in the first quarter, compared with $392,000 in the year-ago quarter, and had revenue of $14.1 million, up form up from $10 million.

Martek Biosciences

Ticker: MATK

Friday's close: $61.60

Week's change: -12%

A fire at a plant of one of Martek's key suppliers, DSM Food Specialties BV of New Jersey, disrupted production of arachidonic acid, which is used to support infant brain development. Columbia-based Martek, which makes nutritional oils for infants, said it would lose $5 million and $10 million in revenue because of the fire. Martek shares fell12 percent.

Ciena

Ticker: CIEN

Friday's close: $3.22

Week's change: -15%

Ciena's stock fell after the company's second-quarter results failed to meet analysts' expectations. The Linthicum telecom equipment maker lost $76.2 million for the quarter ending April 30 (16 cents), compared to a loss of $75.5 million (17 cents) a year ago. Ciena predicted third-quarter revenue would be as much as 30 percent higher than in the second quarter.