Spectrum Group Ltd., the Valhalla residential developer, has been acquired by the American unit of a Swedish construction and real estate powerhouse seeking to build more houses in the Northeast.

Skanska (U.S.A.) Inc. of Greenwich, Conn., completed its acquisition of Spectrum last month, and was expected to announce it on Oct. 10. The deal allows Mitchell C. Hochberg to continue as president and chief executive officer of Spectrum with day-to-day control. It also gives Hochberg what he would only call "a significant" stake in Spectrum, which will become a subsidiary of Skanska.

Spectrum will stay at the Mount Pleasant Corporate Center at 115 Stevens Ave. and will retain its 40 employees, Hochberg said.

The value of the deal was not disclosed. It brings Skanska's capital and construction know-how to Spectrum, so that the company can compete with regional builders like Toll Brothers Inc. and K. Hovnanian Inc.

"This gives us a significant capital base so we could become more competitive (and) do more projects so we don't have to run around and be looking for equity all the time," Hochberg said.

Hochberg said talks began last year, when he met with Skanska representatives seeking a business relationship he hoped would lead to their investing in some Spectrum projects.

"As the discussions developed, they said they would like to have more of a permanent relationship with us instead of just doing one or two deals," Hochberg said.

Skanska (U.S.A.) is the American arm of Skanska AB of Sweden. The American Skanska unit accounts for $1.4 billion of Skanska's worldwide sales of $6 billion. Skanska (U.S.A.) is a group of companies that includes Skanska Real Estate of Greenwich, Conn.