Washington Mutual Inc. signed to sublease 46,464 square feet of office space in Century Square. The company will occupy the ninth and 10th floors. Century Square is a Class A, 536,328-square-foot office building at 1501 4th Ave. in Seattle. Washington Mutual also recently signed a lease for the Second & Spring building at 1100 2nd Ave. It signed for 51,093 square feet of office space on the fourth and fifth floors. Second & Spring is also a Class A office building with a total rentable area of 130,421 square feet. At Century Square, Washington Mutual was represented by Tim O'Keefe and Jesse Ottele of Colliers International. Garth Olsen and Christian Shevchenko of Cushman & Wakefield represented the sublessor, ING Northern Annuity. At Second & Spring, Olsen represented Washington Mutual. The owner, Equity Office Properties, was represented in-house.