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Explicit Lagrange multiplier for firms facing a debt ceiling
1
constraint
*
Jean-Bernard Chatelain
Banque de France, 41-1391, Centre de Recherche, F-75049 Paris, Cedex 01, France
Received 2 August 1999; accepted 10 August 1999
Abstract
This paper provides the explicit expression of investment facing a binding debt ceiling and the explicit expression of the Lagrange multipliers related to the binding debt ceiling constraint. This result allows us to check for misspecification of the parameterizations of these Lagrange multipliers used in Euler investment
equations tests during the 1990’s. 2000 Elsevier Science S.A. All rights reserved.
Keywords: Investment; Credit rationing
JEL classification: D92; G32
1. Introduction
Recent papers tested the Euler equation for capital of the neoclassical model of investment for an infinitely living firm facing quadratic adjustment costs, taxation, imperfect competition on the goods market and an exogenous debt ceiling constraint (see, for example, Gertler et al., 1990; Whited, 1992, and subsequent papers surveyed in Schiantarelli, 1996). In his Journal of Economic Literature survey on the economics of investment, Chirinko (1993, pp. 1902–1904) mentioned that, in these Euler equation tests, ‘‘the endogenous variables that parameterize the Lagrange multiplier related to this
[borrowing] constraint(such as cashflow and net worth) are not accounted for explicitly in specifying the econometric equation, thus blurring econometric interpretations of the statistical tests.It remains uncertain whether significant liquidity and net worth variables are capturing a structural element heretofore missing in the investment equation or are merely reflecting general misspecification.’’ This Lagrange multiplier is parameterized in an ad hoc fashion in the belief that ‘‘the first-order conditions
*Tel.:133-1-4292-4958; fax: 133-1-4292-2766. E-mail address: [email protected] (J.-B. Chatelain) 1
do not provide an analytical answer’’ (Whited, 1992, p. 1435). In this note, we provide the analytical
answer which was missing. This Lagrange multiplier is related to the gap between the standard neoclassical investment behaviour and the (explicit) credit constrained investment. Both expressions are derived in this note, which allows us to check for misspecification in these empirical works.
2. Explicit Lagrange multiplier
The standard partial equilibrium neoclassical model of investment begins with an expression for the value of the firm, which in turn stems from the arbitrage condition governing the valuation of shares. The after-tax return to the owners of the firm at time t reflects capital appreciation and current dividends. In equilibrium, if the owners are to be content holding their shares, this return must equal
0
(12m )r , the after-tax nominal return on riskless (government) bonds between period t and periodt t
0
t11 (rt represents the nominal return before income tax and m is the personal income tax ont dividends and interest income in period t):
(12c ) E [Vt
s
t i,t112Si,t11]2Vitd
1(12m )ut tE [dt i,t11] 0]]]]]]]]]]]]]]]] 5(12m )rt t (1)
Vit
where V is the value of the firm i at time t, S denotes the value of new shares issued at time tit it 11, ct is the accrual-equivalent capital gains tax rate, andutis the dividend received by the shareholder when
2
the firm distributes one unit of post-corporate tax earnings . Therefore, the tax rate on dividends is (12m )ut t. E is the expectation operator conditional on information known at time t. The after-taxt capital gain of the current shareholders thus consists of the change in the market value of the firm less the component of this change due to new share issues. The tax discrimination parameter gt5(12
m )ut t/(12c ) determines the relative tax advantage of dividend income against capital gains. Thet
dividends of the firm i at time t are d . In the absence of bubbles, solving the capital market arbitrageit condition yields the following expression for the firm’s market value at time zero:
t51` s5t21
max ` Vi,t505Et
O P
S D
bis sgtdit2Sitd (2)hp ,I ,L ,d ,S ,K ,Bit it it it it it it tj50 t50 s50
where the firm’s one period nominal discount factor is:
1 ]]]]]
bit5 (3)
12mt 0
]] 11
S D
12c rtt
The entrepreneur in firm i chooses dividends, investment, labour and price of output in maximizing the present value of dividends di,t on date t in an infinite horizon, with the discounted rate of the opportunity cost of internal funds, subject to several constraints. The ‘flow of funds’ constraint defines
2
Under an imputation relationship between corporate and personal taxes, the parameteru 5t 1 /(12s ) where s is the ratet t
firm dividends. Cash inflows include sales, new share issues, and net borrowing, while cash outflows consist of dividends, factor and interest payments, and investment expenditures:
I
dit5(12t) p F(K
s
it i,t21,N )it 2pitC(I ,Kit i,t21)2w Nt it2it21Bt21d
1Sit1Bit2Bi,t212p Iit it (4) where I is its investment at time t, K is capital, N a vector of variable factors of production for firmit it iti at time t, F(Ki,t21,N ) the firm’s revenue function (Fit K.0, FKK,0), C(I ,Kit i,t21) the cost of adjusting the capital stock (CI.0,CII.0,CK,0,CIK,0), w a vector of nominal factor prices att time t, i the nominal interest rate on debt at time t, B is the value of net debt outstanding for firm iit it
I
at time t, pit is the price of final goods at time t, pit is the price of capital goods at time t (incorporating tax considerations), and t is the corporate income tax rate, against which interest payments are assumed to be deductible.
K The firm faces the capital accumulation constraint (with a related Lagrange multiplier lit):
Kit5Iit1s12ddKi,t21 whered is a constant rate of economic depreciation, an exogenous debt ceiling B
*
constraint (Bit#B , related Lagrange multiplierit lit), and a positivity of dividends constraint (dit$0, d
related Lagrange multiplier lit). The firm also faces a downward sloping demand functionw( p ) forit its product with an absolute value of the elasticity denoted e5 2w9( p )p /it it w( p ). Demand is equalit to supply, i.e. output net of adjustment costs, so that the value of sales is the following function of
21
inputs after inversion of the demand function: w (F(Ki,t21,N )it 2C(I ,Kit i,t21))[F(Ki,t21,N )it 2
C(I ,Kit i,t21)]. The derivative of sales with respect to an input X is therefore:
F(K ,N )2C(I ,K ) competitor is given by setting the parameterm to unity each time it appears before the output price in the following equations.
Dividends are substituted directly in the Lagrangean, using the flow of funds constraint as well as investment by the capital accumulation equation. The first-order conditions for capital Kit (Euler equation) is:
In the Euler equation for capital, the discount factor turns out to be ‘corrected’ by a multiplicative
d d
B
marginal cost of debt as a discount rate if lit50, or that the discount factor decreases with the Lagrange multiplier of the debt ceiling constraint (i.e. the discount factor should use the shadow interest rate that would have accepted the firm if she was not facing a quantitative constraint).
Git has been parameterized in an ad hoc manner in several papers following the first ones surveyed by Chirinko (1993). The aim of this note is to find its explicit form, which amounts to finding the
d
explicit form for lit. The Lagrange multiplier related to a quantitative constraint is generally an U C
increasing function of the gap between the ‘notional’ denoted Iit and the ‘constrained’ control
C d
variable (investment for the firm facing credit rationing) denoted I . The expressionit gt1lit is given by the marginal condition on investment in the credit rationing regime:
K
where the marginal costate variable lit is given by the marginal condition on investment in the d
unconstrained regime (lit50):
K I U C
lit5gt
f
pit1mp 1its 2t Ctd I(Iit ,Ki,t21)g
U C
It is a function of the investment rate Iit that would have chosen the firm in the absence of financial constraint. A structural specification of Git is therefore given by:
I C I U C
pit1mp 1its 2t Ctd I(I ,Kit i,t21) gt11
f
pi,t111mpi,t11s12tt11dCI(Ii,t11,K )itg
]]]]]]]]]] ]]]]]]]]]]]]]Git5 I U C I C (9)
gt
f
pit1mp 1its 2t Ctd I(Iit ,Ki,t21)g
pi,t111mpi,t11s12tt11dCI(Ii,t11,K )it3. The case of quadratic adjustment costs
I parameterize the adjustment cost function with its usual quadratic formC(I ,Kit i,t21)5a/ 2(I /i,t
2
Ki,t212n) Ki,t21 (Whited, 1992), so thatCI(I ,Kit i,t21)5a(I /Ki,t i,t212n). The next step is to solve for
C U C
the investment solution facing a binding debt constraint (I ) or not (Iit it ).
On the one hand, when the firm does not face a debt constraint, the usual form is derived by a local approximation near the equilibrium, on the unique stable path. The standard textbook result is that current investment net of long-run investment (which has only to replace the depreciation of the long-run capital stock) is a linear function of the wedge between the current capital stock and the long-term capital stock:
U C
*
*
Iit 5dKit 1ss21 Kds it2Kitd (10)
*
]]]]]]]]]]]]
On the other hand, when the firm faces a binding debt ceiling constraint, the flow of funds equation
*
can be written in the binding debt ceiling regime on date t (Bit5B ), with no dividends (dit it50) and with no new share issues (Sit50):
Dividing the flow of funds equation by the capital stock pi,t21Ki,t21 and using the capital accumulation relation (Kit5Iit1(12d)Ki,t21), there follows a quadratic equation for the ratio of the
I
The first term of the Taylor development of this expression with respect toa, the adjustment cost parameter, which is reasonably below one and small, leads to the following expression (it corresponds to the case a50, i.e. there are no adjustment costs):
3 I I
If the adjustment cost parameterais small enough, then one obtainsv1( p /p )(x 21 /(12t)ap ),0 (the ceiling
it i,t21 it it
of the debt / capital ratio x is necessarily below one). The second solution for investment is negative, and therefore irrelevantit
*
(12t) p F(K
s
it i,t21,N )t 2w Nt t2ii,t21Bt21d
Bit2Bi,t21C
*
]]]]]]]]]]]]] ]]]]j Bits dit 5 I 1 I (17)
p Kit i,t21 p Kit i,t21
Investment depends on after-tax cashflow from operating activities and on the variation of debt. Squared terms of these variables could be added if one takes into account the second-order Taylor development with respect to a.
Explanatory variables of Git are the explanatory variables of the financially constrained investment and of the unconstrained investment function. Git can also be linearised for a small adjustment cost parameter. Then, explanatory variables are the first differences of the variables determining investment facing credit rationing (cashflow from operating activities and the variation of debt) and of the variables related to the unconstrained investment level (the current size of capital of the firm Kit
*
and the cost of capital, which determines the long-run stock of capital K ). This explicit Lagrangeit multiplier suggests specifications closer to the structural one for Euler equation tests of financial constraints. For example, the Whited (1992) intuitions for the choice of the financial variables were right. But these variables ought to have appeared in the first difference in Git. Then, variables related to the unconstrained investment such as the current size of the capital stock and the cost of capital were omitted. Finally, the estimated parameters related to these extra financial variables were not constrained whereas they cannot be anything other than a combination of the parameters to be estimated in the optimization model written at the very beginning, i.e. the mark-up rate, m, and the coefficient of adjustment costs, a.
4. Conclusion
This note derives the explicit expression of investment facing a debt ceiling and of the Lagrange multiplier related to a binding debt ceiling constraint. These two results may help to define and develop tests for investment facing capital market imperfections.
References
Chirinko, R.S., 1993. Business fixed investment spending: A critical survey of modeling strategies, empirical results, and policy implications. Journal of Economic Literature, 1875–1911.
Gertler, M., Hubbard, G., Kashyap, A., 1990. Interest rate spreads, credit constraints, and investment fluctuations: An empirical investigation, NBER Working Paper No. 3495.
Schiantarelli, F., 1996. Financial constraints and investment: Methodological issues and international evidence. Oxford Review of Economic Policy 12 (2), 70–89.
