The acquisition consists of 15 properties with a total value of about SEK4bn ($480m). The portfolio will be owned by a company that is split 50/50 between AMF and Finnish pension company Ilmarinen.
With SEK552bn in assets managed for approximately 4 million customers at 31 March 2015, AMF is one of Sweden's leading pension providers.
AMF's property portfolio currently consists of the wholly owned subsidiary AMF Fastigheter, with commercial properties in the Stockholm region, and a half-owned company, Rikshem, which owns and manages residential and community properties in growth areas throughout Sweden.
AMF said it aims to increase its ownership in real estate. It has for some time been evaluating several possibilities for diversification in markets outside Sweden and plans, with Ilmarinen, to gradually build up a large property portfolio in selected areas of Helsinki.
"We believe that Helsinki will develop positively, with continued urbanisation and growth," said Martin Tufvesson, investment manager for real estate at AMF. "We look forward to working with Ilmarinen to build an independent company with ambitions to grow and work with long-term property management, leasing and development."
AMF's property portfolio is worth about SEK50bn($6bn), including half-owned housing company Rikshem.
AMF is a mutual owned equally by the Swedish Trade Union Confederation and the Confederation of Swedish Enterprise.