UK residential property owner and manager Grainger has signed an agreement with Sigma Capital Group granting the FTSE 250 company the exclusive option for an initial four-year term to acquire certain development opportunities.The residential and urban regeneration specialist has given Grainger the right to acquire development opportunities of 100 units or more that will be sourced by Sigma. The units will create a large-scale private rented sector portfolio across the main cities of England outside Greater London, it said. Under the agreement, Grainger will appraise each development opportunity individually. The two companies have already identified a number of sites that they are looking to progress.Grainger currently expects to fully own the initial developments sourced by Sigma, although in the future it may also look to syndicate its investment to third party investors, which could include Sigma.Sigma is also expected to act as development manager on the majority of projects and will earn a profit share on each development, split into a sourcing fee and a development management fee, the company explained.Grainger chief executive Andrew Cunningham said: "This agreement leverages both Sigma's excellent relationships with Local Authorities and housebuilding partners across the UK and Grainger's proven track record in managing residential property, whilst providing an innovative new avenue for investment."We are at the forefront of the private rented sector and remain committed to delivering high quality new homes, benefitting local communities whilst delivering shareholder value."