Profit at Freddie Mac leaped by nearly a third, reaching $564 million, or 75 cents a share, in the third quarter, compared with $425 million, or 58 cents a share, in the same period last year.

The company showed a similar rise for the nine months ended Sept. 30, posting earnings of $1.63 billion ($2.17 a share), up from $1.23 billion ($1.68) for the 1998 period.

Earnings met analysts expectations. The stock closed yesterday at $48.81 1/4, down $1.56 1/4.

McLean-based Freddie Mac is a congressionally chartered, stockholder-owned corporation that buys home mortgages from the original lenders to supply additional capital to the nation's housing markets.

Company officials attributed the good showing to strong growth in its mortgage portfolio and to improved credit performance. Revenue, at $1 billion, was up from $821 million in the 1998 third quarter, and net interest climbed to $610 million from $480 million a year earlier, and credit-related expenses totaled $36 million--a plunge of $43 million from a year ago.

* Black & Decker Corp. said that it earned $75.3 million (85 cents a share), up 13 percent from $66.6 million (72 cents) from the same quarter a year ago. The company's reported $1.111 billion in sales during the third quarter of 1999 compared with sales of $1.108 billion in the same quarter the year before.

The company beat analysts expectations by 2 cents a share. The stock shot up $1.50 during the day but closed virtually unchanged yesterday at $43.50.

The Towson-based toolmaker reported net income of $185.2 million ($2.09) for the nine months ended Oct. 3, compared with a net loss of $846.4 million for the nine months ended Sept. 27, 1998. However, the first nine months of 1998 included a $900 million write-off of goodwill, a $107.7 million after-tax restructuring charge and a $13.4 million after-tax gain on the sale of businesses.

The company said a decline in sales for the first nine months of 1999 to $3.17 billion from $3.29 billion in 1998 reflected the effects of divestitures and foreign currency translation.

* Proxicom Inc. of Reston reported third-quarter net income of $1.5 million (5 cents a share), compared with a net loss of $20.9 million in the same period of 1998.

The previous year's earnings include $18 million in stock-based and other compensation that Proxicom didn't have in the 1999 third quarter.

Proxicom, an Internet consulting company, said its third-quarter revenue increased 88 percent, to $23.6 million.

* Startec Global Communications Corp., a Bethesda-based international phone carrier that markets to ethnic groups, posted a smaller-than-expected third-quarter loss of $1.19 a share. Analysts had anticipated a loss of $1.24 a share.

The company had revenue of $76.6 million--about 62 percent more than the third quarter of 1998--as its customers more than doubled.

Startec closed at $16.25 yesterday, up 12 1/2 cents.

* GRC International Inc., a Vienna-based management and engineering consulting firm, reported a 25 percent increase in revenue, but net income fell to $2.4 million (21 cents a share) from $3.1 million (30 cents) because the company could no longer take advantage of tax-related benefits from losses in previous years.

GRC's revenue for the quarter ended Sept. 30 grew to $45.8 million--including $2.5 million from Management Consulting and Research Inc. that was acquired during September--from $36.8 million a year earlier.