(Sharecast News) - Social housing investor Residential Secure Income has exchanged contracts to acquire 478 retirement homes from Places for People for £40.2m.Residential SI told investors on Monday that the purchase of the properties from Places for People, one of the UK's largest housing associations, would generate a yield in line with its previous retirement home acquisitions.The London-listed group has already completed the acquisition of 421 of the properties, immediately producing income, and will complete its acquisition of the remaining 57 properties within three months.Residential revealed that the portfolio consists primarily of one-bedroom flats located across 284 purpose-built retirement schemes, over 93% of which are located in Southern England and the Greater London area.The portfolio, which will continue to be managed by Girlings, part of the Places for People Group, is leased to retirement-aged residents on RPI-linked assured tenancies which offer lifetime security of tenure.As a result of the acquisition, Residential SI has invested a total of £215m in assembling a portfolio of 2,414 residential units.Ben Fry of ReSI Capital Management, the investor's fund manager, said: "Our strategy continues to be focused on delivering a secure, long-term income stream to shareholders. We are making good progress in building a high-quality portfolio that meets these disciplined investment criteria, and expect this progress to continue."As of 1230 BST, RESI shares had slipped 0.14% to 95.67p