Investors punished Human Genome Sciences Inc. last week after the Rockville company said research and development costs caused its third-quarter loss to triple.

The biotechnology firm's net loss grew to $75.1 million (58 cents per share) in the three months ended Sept. 30, from $24.9 million (19 cents) in the same period last year. The company's third-quarter revenue held steady at $1.6 million.

Human Genome Sciences' loss included a $32.1 million one-time charge, but its shares tumbled 20 percent on the news last week to close at $9.09.

The Washington Post-Bloomberg regional stock index closed off 0.2 points at 161.40. The NVTC Potomac Tech 60, made up of 60 tech firms with a large local presence, closed at 571.82, up 14.6 points.

Shares of SafeNet Inc. of Baltimore fell $2.26 the day after the network security firm said it agreed to buy Cylink Corp. of Santa Clara, Calif., in an all-stock deal. The company said the deal was worth $35.4 million, based on Wednesday's closing price, but its value dropped to $30.9 million Thursday after shares of SafeNet fell to $16.79.

Cylink is a 175-person company that provides technology to government clients. Shares of SafeNet closed at $16.85 Friday, down 15 percent for the week.

Pittston Co., a Richmond firm that provides security systems and freight transportation services, was also among the region's biggest losers last week, despite recording improved earnings. The firm's net income rose to $22.1 million (41 cents a share) in the three months ended Sept. 30, compared with $9.2 million (17 cents) in the same period last year. Pittston's revenue for the third quarter rose to $953.7 million from $884.3 million in the year-ago period.

Shares of Pittston closed at $19.61, down 16 percent.

Group 1 Software Inc. posted increased earnings and raised its expectations for the rest of the year last week.

The Lanham software company reported net income of $2 million (28 cents a share) in the three months ended Sept. 30, compared with $955,000 (14 cents) in the same period of last year.

The company's fiscal second-quarter revenue rose to $25 million from $22.3 million in the year-ago quarter, and Group 1 forecast a revenue increase of 11 to 12 percent for the second half of its fiscal year. The company had previously predicted an increase of 10 percent.

Group 1 was one of the leading gainers last week, up 23 percent to close at $20.05 a share.

Improved earnings helped to boost shares of Igen International Inc. of Gaithersburg.

The biotech firm cut its loss for the second fiscal quarter to $8.3 million (35 cents per share) from $12.1 million (64 cents) in the same period last year. The company's revenue rose to $8.4 million for the three months ended Sept. 30, from $5.8 million in the year-ago period.

Shares of Igen closed at $36.49, up 18 percent.