Riggs National

Ticker: RIGS

Friday's close: $21.84

Week's change: +20%

Shares of Riggs soared last week after it hired the investment bank Lehman Brothers to advise it on a possible sale. Riggs, the largest commercial bank based in the Washington area, has been under scrutiny from regulators because of its relationships with foreign embassies. The company's longtime chairman, Joe L. Allbritton, resigned from the board last week.

Spherix

Ticker: SPEX

Friday's close: $6.00

Week's change: +21%

Spherix's stock got a lift last week as the company reported that its low-carb sweetener, Gaio tagatose, would be used in chocolate sold in Australia and New Zealand. The sweetener is to be included in a new line of diet chocolate products produced by Miada Sports Nutrition of New Zealand. Beltsville-based Spherix has both information technology services and biotechnology products.

Convera

Ticker: CNVR

Friday's close: $2.97

Week's change: +16%

Stock in Convera of Vienna rose after the company reported a narrower loss in the first quarter of 2004, compared with the same quarter a year ago. Convera lost $4.8 million (14 cents a share), compared $5.9 million (20 cents) in 2003. Revenue also improved , to $8.2 million from $7 million. Convera produces search and categorization software.

ManTech International

Ticker: MANT

Friday's close: $18.64

Week's change: -27%

ManTech International's stock fell last week as the company lowered its profit outlook for the second quarter and the full year. The Fairfax company, which provides the government with information-technology services, said it expects to earn between $1.17 and $1.21 per share in 2004, down from its earlier estimate of $1.38 to $1.42. The change came from revenue adjustments on a contract.