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Bank Competition, Information Choice and Inefficient Lending Booms

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2. If the noncontestability constraint in equation (14) binds (i.e. λ > 2(q−¯p)<br />

ε<br />

+ 4γ<br />

ε(R−r) ),<br />

it must hold with equality:<br />

max<br />

Q=(S, (D,d))<br />

Π[Q]<br />

s.t. Π[Q] = γ|Q| (29)<br />

Thus, any equilibrium has to maximize the size |Q| of the portfolio whilst maintaining<br />

an average profit per loan of exactly γ. Let me assume additionally that<br />

q is such that the portfolio F that comprises of all projects financed at (R, r) is<br />

noncontestable (i.e. q ≥ ¯p −<br />

γ<br />

R−r ).<br />

To solve this problem, I first characterize what the largest possible portfolio Q is that<br />

satisfies Π[Q] = γ|Q| when repayment terms are exogenously fixed at some (D, d),<br />

where D ≤ R <strong>and</strong> d ≤ r. To yield exactly γ per loan, the average probability of<br />

success in the portfolio must be equal to<br />

∫<br />

A λ [Q] =<br />

S∈Q<br />

∫<br />

S∈Q<br />

p dE λ (p)<br />

dE λ (p) = ρ − d + γ<br />

D − d<br />

This condition is met by many symmetric portfolios that all have repayment terms<br />

(D, d). But the size of the portfolio can only be maximal if the portfolio is chosen<br />

in a pecking order that starts with the best projects <strong>and</strong> proceeds in the order of<br />

expected success probabilities towards worse ones: to see this, imagine that the<br />

portfolio selection would not follow a cut-off structure, <strong>and</strong> that some nonzero mass<br />

m of projects with average success probability π m was denied financing whereas a<br />

subset of projects of equal size but worse average success probability π n < π m was<br />

financed. Then, by exchanging in the portfolio the worse projects projects for the<br />

better ones, one can increase the nominator of eqn (30) by m·(π m −π n ) whereas the<br />

denominator stays the same. This “excess” in success probability can be used to<br />

enlarge the portfolio size by financing an additional mass of previously unfinanced<br />

projects that have worse quality than the portfolio average, whereby the mass is<br />

chosen such as to restore the average success probability to its original value. This<br />

shows that a portfolio which does not respect the pecking order of “best loans come<br />

first” will not be maximal in size.<br />

Thus, there will be a unique cut-off ˆq that will be determined by meeting the average<br />

success probability condition:<br />

2¯p + 2ˆq + λε<br />

= ρ − d + γ<br />

4<br />

D − d<br />

2(ρ − d + γ)<br />

⇒ ˆq =<br />

D − d<br />

− ¯p − λε<br />

2<br />

This expression makes it obvious that the cut-off is decreasing in D, so portfolio<br />

size is increasing in D; thus when D is also chosen, we must have D = R. Finally,<br />

36<br />

(30)<br />

(31)

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