PEC Solutions

Ticker: PECS

Friday's close: $11.51

Week's change: +11%

Shares of the Fairfax-based professional services firm, which works on government computer networks, surged after it bought Integrated Information Technology Corp., a government contractor that engineers satellite communications. PEC paid $33 million in cash plus $2 million in employee retention bonuses.

MedImmune

Ticker: MEDI

Friday's close: $25.05

Week's change: +4%

MedImmune was bolstered last week when Morgan Stanley decided to upgrade the stock from "equal" to "overweight." The biotechnology company has suffered over the past year from disappointing sales of its nasal influenza vaccine, FluMist. But Morgan Stanley said investors have undervalued the Gaithersburg company's product pipeline.

Riggs National

Ticker: RIGS

Friday's close: $20.65

Week's change: -5%

Shares of Riggs slid as controversy swirled about transactions related to embassy accounts. The District-based bank was fined $25 million last month, but federal regulators admitted last week they did not act quickly enough. Also, regulators acknowledged the bank examiner who oversaw Riggs for several years was hired weeks after he left the government in 2002.

Manugistics Group

Ticker: MANU

Friday's close: $4.00

Week's change: -10%

Stock in the Rockville company, which helps companies improve their supply chains, was battered after it disclosed it would lose money for the quarter. Manugistics blamed lower software sales for a projected loss of $7 million to $8 million (9 cents to 10 cents a share) for the first quarter of its fiscal year, which ended May 31. The company will release detailed financial data later this month.