The 138,000-sf six-story building with views of Elliott Bay was developed by Selig Real Estate Holdings XXV, an entity of Martin Selig Real Estate, at a cost of $25 million after F5 Networks preleased the entire building in October 2006. The lease was meant to provide expansion space for F5, whose three corporate headquarters buildings are located adjacent to 333 Elliott.

Classmates is subleasing the top two floors. While Classmates' negotiated sublease rate was not revealed in F5's SEC filings, F5 detailed its lease rate and has said it is "taking a loss" on the sublease. F5's starting annual rent, which it must start paying as soon as it occupies the building, is $3.43 million per year, which works out to $24.99 per sf, not including payment of certain operating expenses, including utilities and real estate taxes, for which the company also will be on the hook. F5's base rent will increase by $1 per sf every year of the 10-year lease, according to SEC documents.

Classmates Online is a part of Classmates Media Corp., which is a wholly owned subsidiary of publicly held United Online Inc. The company is relocating in order to expand because it had run out of room at its Renton location near the Ikea retail store. The deal for its new office space in Seattle reportedly includes signage rights.