10ing function of the future value of the collateral, we assume that borrowing capacity is an increas-ing function of the current value of the collateral. The same modelling choice has been made byMendoza (2010), Jeanne and Korinek (2010b) and Mendoza and Smith (2006), and is justified bythe work of Cordoba and Ripoll (2004) and Kocherlakota (2000) who show that collateral con-straints specified with next-period price of collateral asset do not yield quantitatively significantdifferences in response to shocks.Consumers maximize (1) subject to the budget constraint (3) and the collateral constraint (4). Theutility maximization problem of therepresentative consumer(i.e., variables without the subscripti) can be written as:maxb1;b2;q28>>>:ub1+(1q1)p0+E0ue+b2+(q1q2)p1+p1b1RL1+q2y+p2b2RL2l(b2q1p1)9>>=>>;:(5)Solving this problem backwards, the first order conditions are:p1=yu0(c1);u0(c1) =RL2+l;u0(c0) =RL1E0u0(c1):(6)The first equation represents the asset pricing condition for the economy. The second and thirdequations are the Euler equation for consumption in period 1 and 0, respectively.5Consumers’ demand of loansIn order to allow for market power in the banking sector, we model the market for loans in a Dixitand Stiglitz (1977) framework.6That is, we assume that loan contracts bought by consumers area constant elasticity of substitution composite basket of slightly differentiated financial products—each supplied by a bankj— with an elasticity of substitutionz(which will be the main deter-minant of the spread between bank rates and the risk-free rate).In particular, the consumeri, in order to obtain a loan of a given sizebi;t, needs to take out a con-tinuum of loansbij;tfrom all existing banksj, such that:bi;tZ10bz1zij;td j!zz1(7)5Details on the the derivation of the equilibrium conditions are reported in Appendix A.6Benes and Lees (2007) and Gerali, Neri, Sessa, and Signoretti (2010) take a similar approach