Even a down economy can provide business opportunities, as Washington-based Liquidity Services is proving in growing its work liquidating government and commercial excess assets.

The 730-employee company runs Web sites that function as auction markets for wholesale, surplus and salvage items from commercial firms and federal, state and local government bodies.

In the case of the Defense Department, for instance, Liquidity resells everything from military trucks to industrial equipment, using e-commerce to limit the cost of moving items around. It recently announced the extension of two Pentagon contracts, one to sell scrap property and another to sell surplus property.

The company also said it will pay $140 million for Jacobs Trading Remarketing Business, a company that handles retail returns and has a relationship with retail behemoth Wal-Mart.

Liquidity’s sales have surged in recent months. In its last earnings report in August, Liquidity Services said its third-quarter revenue grew about 18 percent from the same period a year earlier, to $86.1 million.

“It’s fair to say that we’re a counter-cyclical business,” said William P. Angrick III, Liquidity’s chief executive and chairman. “Corporations and, more recently, federal and state and local agencies are looking for efficiencies, they’re looking for cost savings. . . . That plays into our strengths.”

However, the business has had some bumps. In the same August earnings announcement, it reported a loss of $1.1 million (a loss of 4 cents per share), a significant drop from its nearly $3 million profit (11 cents) in the same three-month period a year earlier.

The company said the loss came in connection with its plans to close its United Kingdom subsidiary, known as Liquidity Services Limited. Angrick said that Liquidity posted robust profit when the costs of shutting down that unit were excluded.

He promised continued growth for the company, which was founded in 1999 and went public in 2006, and said Liquidity Services expects to grow to 1,000 employees within a year or two. The company’s work is split almost evenly between commercial and government organizations, based on the value of the merchandise Liquidity sells.

Investors, too, are bullish on the company’s growth. RBC Capital Markets said in its June note that the company “dominates its niche space, as it enjoys exclusive supply from its long term contracts and has very few large competitors.”

Angrick said the economic downturn will continue to motivate sellers, who are seeking to find cash where they can, as well as buyers, who might have bought new in the past but are now looking for used items.

“We respond to the need to be more efficient,” he said.