Internet service provider PSINet Inc. of Herndon yesterday reported a second-quarter operating profit of $200,000 on revenue of $123.8 million.

The company's net loss available to common shareholders in the period was $62.0 million, but before taking into account interest, taxes, depreciation and amortization--a calculation known as EBITDA--PSINet posted a $200,000 profit. That compares with a net loss to common shareholders of $54.5 million on revenue of $53.7 million a year ago. Internet service providers and telecommunications firms use EBITDA as a measure of financial performance because of the high costs of depreciation on costs associated with building their data networks.

That is particularly true for PSINet, whose rapid expansion and flurry of acquisitions contributed to $34.4 million in depreciation and amortization expenses in the quarter.

For more than a year, PSINet executives have said their company was on the verge of positive EBITDA. Yesterday's announcement that the firm finally crossed that threshold pleased industry analysts.

"This is very positive news," said Ulric Weil, an analyst with investment bank Friedman, Billings, Ramsey Group Inc. in Arlington. "They are no longer burning cash. From an operating point of view, they are creating cash."

For the first six months, the company reported a loss available to common shareholders of $67.8 million, compared with $70.9 million a year earlier. Six-month revenue grew to $228.7 million, vs. $98.2 million a year ago.

* Allied Capital Corp., a District firm that finances businesses, reported that profit jumped in the second quarter because it increased its new investments and focused on improving the returns it gets from its assets.

Net income for the quarter was $22.1 million, up 53 percent from $14.5 million last year; on a per-share basis, net income rose 36 percent, to 38 cents from 28 cents, on fewer shares. Interest and related income from its loan portfolio increased 56 percent, to $33.2 million from $21.3 million. Gains from investments rose to $5.5 million from $5.3 million.

During the quarter, when it made a record $183.1 million in debt and equity investments, Allied's assets topped $1 billion.

In the first six months, profit was $40.7 million (70 cents), down 13 percent from $46.5 million (89 cents) last year, which included a one-time profit from securities sales. Portfolio income rose 5 percent, to $60.7 million from $58.2 million; gains on investments fell 18 percent, to $10.3 million from $12.5 million.

* Host Marriott Corp. of Bethesda reported net income of $74 million (31 cents a share) in the second quarter, a 12 percent gain over the $66 million (28 cents) reported for the same quarter the year before.

Host Marriott has been operating since January as a real estate investment trust, after leasing most of its 124 hotels to a separate operating company. In common with other REITs, which distribute most of their rental income to stockholders, the company also reported funds received from operations, which increased to 48 cents a share in the quarter, a 7 percent gain from the 45 cents the company would have reported had it been operating as a REIT last year.

Revenue per room was 3.7 percent higher in the second quarter over the year before, helping boost rental income to $325 million for the quarter, vs. $233 million pro forma for the prior year quarter.

* W.R. Grace & Co., a chemical company that is relocating from Boca Raton, Fla., to Columbia, said it earned $25.7 million (37 cents a share) in the second quarter, compared with $25.5 million (34 cents) a year earlier.

Revenue rose slightly, to $373 million from $370 million.

The quarterly report excludes $5.7 million in income from discontinued operations.

For the six months, Grace earned $45.7 million (65 cents), compared with a loss of $500,000 last year. Revenue was $719 million, compared with $711 million.

Chief executive officer Paul J. Norris said Grace enjoyed strong results in its catalysts and silica-products units, as well as in its building-materials business.

* Proxicom Inc. of Reston, an Internet consulting and development company, said net income for its second quarter was $764,000 (3 cents per share), compared with $65,000, or break even, during the same quarter last year.

Revenue for the second quarter reached $16.2 million, up 54 percent from $10.5 million in 1998.

For the first six months, Proxicom reported net income, excluding an acquisition-related charge and a non-cash beneficial conversion charge, of $848,000 (4 cents). That's compared with a net loss, excluding an acquisition-related charge, of $343,000 in the first six months of last year.

Six-month revenue was $29.5 million, compared with $18.6 million in the previous year.

During this second quarter, Proxicom opened an office in Rome through a joint venture with Ericsson Telecommuncazioni SpA.