Norwalk, CT-based FactSet Research Systems Inc. expanded into an additional 8,879 square feet in the Peninsula Office Park at 2600 Campus Drive in San Mateo. The eight-year deal also includes an amendment to the contract for an additional 2,685 square feet if Equity Office does not lease the space out by June 2008. FactSet now occupies a total of 27,129 square feet in the building.