This is not currently available as the funding for 2009-10 has already been fully committed. Social Homebuy allows tenants of participating Councils and housing associations to buy their rented home on shared ownership terms, with a proportion of the usual Right to Acquire discount. FirstBuy a scheme for first-time buyers announced in the 2011 Budget. Under it first-time buyers can get help to fund the difference between a 5% deposit and a 75% mortgage. It is only available on selected newbuild schemes. The top-up equity is provided in equal shares by the HCA and the developer. Private sector shared equity or, as it is sometimes known, "investor shared equity", operates quite differently in that there is no element of taxpayer subsidy. Instead, third party investors provide the difference between the buyer's deposit and (typically) a 75% mortgage, in return for an equity stake in the property and a rent. These schemes are run over 5 or 10 years (sometimes with a 'hardship' extension), meaning that at the end of the relevant period, the owner has to buy out the equity stake at the relevant percentage of the then market value. There is generally no penalty on early redemption or partial buy-backs. Thus, equity sharing can be seen as a step up to full ownership of a property. Although investor shared equity is, on the face of it, more expensive than public sector schemes, because of the need to pay rent on the non-owned portion, it nevertheless holds significant advantages:   In economic theory, ownership is studied in the field of contract theory. Specifically, Oliver Hart (1995) has argued that ownership matters in the context of incomplete contracts. When some future contingencies cannot be taken care of in a contract today, then negotiations will take place tomorrow. Ownership improves the bargaining position in these negotiations. As a result, today an owner has stronger incentives to make relationship-specific investments (i.e., the hold-up problem is mitigated). In this framework, Schmitz (2017) has shown that shared ownership of an asset can be desirable today, even though tomorrow it is optimal to give the asset to the party who values it most. The reason is that shared ownership yields more balanced investment incentives of the involved parties. The optimal ownership shares depend on whether the investments are embodied in the physical capital (so that the owner can always seize the returns) or in the parties’ human capital.