CommonWealth Partners bought the Russell Investments Center in Seattle from Northwestern Mutual in a $480 million transaction. The deal marks the largest single asset office sale in Western U.S. since 2006.

Russell Investments Center is a class-A+, 872,026-sq.-ft. office building. Located in the Seattle Central Business District, it was constructed in 2006 and is currently 95 percent leased to tenants in the technology, bio-tech, retail and finance sectors. Russell Investments, JP Morgan Chase, Boeing, Zillow and Nordstrom have offices at the property.

Kevn Shannon, vice chairman with CBRE, along with Todd Tydlaska, Ken White, Tom Pehl, Tom Abbott and Lou Senini, represented the seller in the transaction.

“We are pleased to have generated significant value for our policy-owners with this transaction,” said Paul Hanson, managing director for real estate investments with Northwestern Mutual, in a statement. “Our real estate investment strategy typically focuses on long-term holds, but the Seattle real estate market rebounded more quickly than we anticipated and we were able to realize significant gains in a fairly short period of time.”