F&M Bancorp's announcement that it will be bought by Mercantile Bankshares for $500 million was cheered by investors, pushing up the stock 39 percent for the week.

F&M rose 37 percent, or $11.49, the day it announced that Mercantile agreed to pay $46 a share for the 48-branch bank, based in Frederick. The deal will give Mercantile, with 185 branches, the second-largest market share in Maryland. The companies said that about 21 branches from both banks would be closed because of the acquisition. Mercantile's stock closed Friday at $33.25, while F&M closed at $42.77.

The Washington Post-Bloomberg regional stock index closed Friday at 154.20, up 0.88 points for the week. The NVTC Potomac Tech 60, made up of 60 area technology companies, closed at 509.89, up 10.31 points.

Investors reacted positively to news that Sylvan Learning Systems intends to sell its kindergarten through 12th grade units and focus solely on the higher-education market. The company also said it will disband its venture capital unit, Sylvan Ventures. The company will consist of an on-campus unit, Sylvan International Universities, and an online operation. Sylvan projects that its higher-education revenue will increase about 19 percent in 2003, to $450 million to $475 million. Sylvan also said it expects to sell its elementary and secondary-school businesses for $275 million to $300 million. Shares of the Baltimore education company rose 29 percent to close at $15.41 Friday.

Increased sales of nutritional oils helped boost Martek Biosciences' first-quarter net income. The Columbia biotech earned $2.1 million (8 cents a share) in the three months that ended Jan. 31, up from a loss of $2.9 million (15 cents) in the same period a year earlier. The company's revenue for the quarter rose to $20.5 million from $6 million in the year-ago period. Shares of Martek closed at $25.32, up 17 percent.

GTSI shares fell after the Chantilly government contractor said it would post a loss for the first quarter. GTSI said dealys in government spending and a potential war with Iraq caused it to lower expectations for the quarter ending March 31. The company previously said it had hoped to break even. Last year the company earned $541,000 during its first quarter. Shares of GTSI fell 12 percent to close at $7.25.