Item # 4 SEMINAR IN LAW, ECONOMICS, AND ORGANIZATION RESEARCH Professors Louis Kaplow, Lucian Bebchuk, Oliver Hart, and Kathryn Spier Monday, October 18 Pound 108, 12:30 p.m. “ Collateral Damage? Derivatives Trading and Empty Voting” Holger Spamann Collateral Damage? Derivatives Trading and Empty Voting Holger Spamann Harvard University Octob er 12, 2010 [Preliminary and incomplete] AbstractThispaperanalyzesam o d e l o f p a r a l l e l t r a d i n g o f vo t i n g s e c u r i t i e s a n d d e r i va t i ve s w i t h p e r f e c t l y n e g a t i ve l y c o r r e l a t e d c a s h - ow s , s u ch a s b o n d s a n d c r e d i t d e f a u l t s wa p s . I n t h e p r e s e n c e o f n o i s e f r o m l i q u i d i ty t r a d e r s , a h e d g e f u n d c a n s o m e t i m e s p r o t a b l y a c q u i r e a vo t i n g b l o ck o f s e c u r i t i e s ove r - h e d g e d by a n e ve n l a r g e r b l o ck o f d e r i va t i ve s , s u ch t h a t i t s i n c e nt i ve s a r e t o vo t e f o r d e c i s i o n s t h a t red u ce t h e va l u e o f t h e s e c u r i ty ( " e m p ty vo t i n g " ) . At o t h e r t i m e s , t h e h e d g e f u n d vo t e s t o i n c r e a s e t h e va l u e o f t h e s e c u r i ty. T h e r e s u l t i n g u n c e r t a i nty a n d t h e h e d g e f u n d s p r i va t e i n f o r m a t i o n w i t h r e s p e c t t o i t s ow n vo t i n g p l a n s e n a b l e t h e h edgefundtoreaptradinggains.Ascollateraldamage, s o c i a l va l u e i s d e s t r oye d e a ch t i m e t h e h e d g e f u n d vo t e s t o m i n i m i z e t h e va l u e o f t h e s e c u r i ty. D e r i va t i ve m a r ke t p a r t i c i p a nt s c a n p r o t e c t a g a i n s t t h i s s t r a t e g y by i n c l u d i n g p o s i t i o n l i m i t s a n d p ayo u t i n f o r m a t i o n p o o l i n g i n t h e i r d e r i va t i ve c o nt r a c t s . In rec ent years, comm entators have voiced grave con cerns ab ou t "e mpty votin g" en abled by d erivative s (esp e cially Hu an d Black 2006, 2007, 2008a, 2008b ). The f ear is that ce rtain owne rs of voting se curities such as b on ds or sh are s will us e d erivatives to he dge more than all th e cash - ow attached to the sec urities . As a cons equen ce , like an over-insu re d h om e-own er might p ref er to s ee his hou se bu rn d own, thes e owne r-voters might f avor an outcome that reduces the valu e of their sec urity. Thu s de rivative s might s et ince ntives for value- des troyin g votin g b e havior. This conc ern h as b een partic ularly strong with resp ect to cred it d efau lt s waps (CDS ) an d b on ds. Ref erring to e mpty votin g, George S oros (2010) h as calle d CDS a "lice nse to kill," an d fe llow f und manager David Einh orn has calle d CDS "in herently u nsaf e" (Se nde r 2009). Te r e n c e M . C o n s i d i n e Fe l l o w , H a r va r d L a w S ch o o l ; h s p a m a n n @ l a w . h a r va r d . e d u . Fo r h e l p f u l d i s c u s s i o n s , I t h a n k R u ch i r A g a r w a l , P h i l i p p e A g h i o n , L u c i a n B e b ch u k , E ¢ B e n m e l e ch , S t e f a n o G i g l i o , O l i v e r H a r t , S c o t t H i r s t , A n d r e i S h l e i f e r , t h e H a r va r d L a w S ch o o l c o r p o r a t e f e l l o w s l u n ch g r o u p , a n d s e m i n a r p a r t i c i p a n t s a t H a r va r d L a w S ch o o l a n d H a r va r d U n i v e r s i ty s D e p a r t m e n t o f E c o n o m i c s . Fo r g e n e r o u s n a n c i a l s u p p o r t , I t h a n k t h e P r o g r a m o n C o r p o r a t e G o v e r n a n c e a t H a r va r d L a w S ch o o l , t h e J o h n M . O l i n C e n t e r f o r L a w , E c o n o m i c s , a n d B u s i n e s s a t H a r va r d L a w S ch o o l , a n d H a r va r d U n i v e r s i ty. 1 Not all agree , h owever, th at d erivatives, and CDS in particu lar, p os e s uch ris ks . The Intern ational Swap s and De rivative s Asso ciation (IS DA) claims that the fears are not ju sti ed with res p ect to CDS (Men gle 2009, p p. 10-11). A wou ld -b e em pty voter, so th e argum ent go e s, wou ld have to p ay a high CDS price re ecting the in creased de fault probability of th e b on d. Give n this h igh price, the strate gy wou ld n o lon ger b e p ro tab le . This pap er provid es a m o d el to as ses s such claim s, an d shows th at fe ars of a de stru ctive e/ec t of a parallel derivatives market on corp orate voting are ind eed j usti ed . To do so, it e mb ed s into a s tan dard trading mo del (Kyle 1984; Kyle and Vila 1991) parallel trading of (a) voting s ecu ritie s an d (b ) derivatives with exactly opp os ite cas h- ows and n o voting rights. (For con cretene ss, one may think of the s ecu rity as a b on d and the derivative as a credit def ault s wap.) In the m o d el, a large trad er a "h edge f un d" acquires a blo ck of voting se curities . In parallel, the fu nd also ac qu ires a p osition in de rivatives that is smaller or large r than its sec urities p osition, as the case m ay b e. Whe n th e he dge fu nd s de rivative p osition is larger than its s ecu ritie s p osition (i.e., th e he dge fun d is "net short"), it maximizes its payo/ by votin g to reduce the valu e of th e se curity. Ration al market particip ants ("market makers") anticipate th e he dge f und s gene ral strategy. Bu t in any given c ase, the y d o n ot know the size of the he dge fu nd s de rivative p osition b e caus e th e h ed ge f und s trades are con foun ded with th os e of liquid ity trad ers with varyin g exogenou s d emand for de rivative s. Liquidity trad ers thus p rovide c am ou age for th e hed ge fu nd, and prices of se curities and d erivative s re ect an ave rage of th e h igh and low p ayo/ of the sec urity. Th e h edge fu nd gain s by b uyin g se curities relatively cheaply (and p oss ib ly sellin g d erivatives exp en sive ly) wh en it votes to maximize the se curities value, and it gains by buying derivatives relatively cheap ly when it votes to min im iz e th e se curities value . Th at is, the hed ge fu nd gains by trad ing on the un certainty th at its own voting b eh avior gene rates. Th e cos ts are b orn e by the liquidity traders. As collateral d amage , so cial value is des troyed each time the he dge f un d votes to min imiz e the value of a s ecu rity. 1The mo del s hows that the problem of value- des troyin g vote s is more seve re in more "liqu id " d erivatives marke ts , that is, markets in wh ich trad es by liquidity trad ers are su b jec t to greater u ctuations an d trading cos ts are lower. Th is is a cau se for con cern give n d erivatives markets explosive growth over last d ecad e or so. At the s ame tim e, the mo de l also sh ows that the m a jor costs of th e em ptyvotin g p rob le m are intern alize d by the participants of the derivatives market, notably liquidity traders. The se p artic ip ants th ere fore have th e (almos t) corre ct ince ntives to ad opt a contractual s olution to the problem, which the pap er outlin es .The pap er als o b rie y revie ws legal d o ctrines th at may stand in way of value -de stroying emp ty votin g, bu t it argu es that the cu rrent law d o e s not protect against all su ch voting. Abs ent le gal or contractual c on straints, th e marke t s ability or inability to inf er the hed ge f und s b e havior f rom ob served trade s is th e key d eterminant of 1T h e i n c e n t i v e s f o r s e l f - r e g u l a t i o n a r e s l i g h t l y t o o w e a k b e c a u s e d e r i va t i v e m a r k e t p a r t i c i p a n t s d o n o t i n t e r n a l i z e t h e n e g a t i v e e /e c t s o n o t h e r s e c u r i ty h o l d e r s . 2 pro tability of the he dge f un d s s trategy. On the one hand , if th e market cou ld p e rf ectly obs erve th e he dge fu nd s p os itions , it c ou ld p erfe ctly predict the voting outcome (sin ce only a hed ge fu nd with more de rivative s th an sec urities wou ld rationally vote to red uc e th e valu e of th e sec urities ). In that case , however, th e he dge f und would have to p ay f or the de rivative e xactly wh at the d erivative contract is going to pay ou t, an d so th e hed ge f un d could not m ake any pro ts. On the othe r h and, if th e market c ou ld not learn ab out th e h edge f un d s p osition un de r any circ ums tan ces , then th e hed ge fu nd c ou ld take ve ry large p ositions without a/ec tin g th e p rice an d make ve ry large p ro ts by goin g short derivative s if the market pric e presu mes (f alse ly, given th e he dge fu nd s interve ntion) that the value -re du cing de cision will b e ad opted, an d by going long de rivatives in the op p osite case . In re ality, and in th e mo del, large trade s will a/ec t th e price of b oth sec urities an d derivatives. The trades reveal information , in th is cas e ab out th e h edge fu nd s p osition. Th is inf ormation , howe ver, is partially hid den by the n ois e from liqu id ity trade s. Th e p rob le m f or marke t makers, b oth in th e real world an d in the mo del, is wh at inf erenc es to d raw f rom th e imp erfe ctly ob served in formation. The emp hasis on trading and m arket makers in feren ce p rob le m sets th e pres ent mo de l ap art from Bolton an d Oe hmke (2010). Bolton and Oeh mke also mo del the interaction of d erivatives and c ontrol rights. Con cretely, they analyz e the e /ect of CDS availability on ren egotiation in an inc om plete contracting mo del of deb t with s trategic d ef au lt. In th eir mo d el, creditors ability to hed ge the ir exp osure to the d ebtor w ith CDS c ontrac ts in creases creditors b argain ing p ower in rene gotiation . This red uc es th e inc id en ce of strate gic de fault and the ref ore has the b en e c ial e /ect of inc re as in g the de bt cap acity of the rm; at the same time, overin surance may lead to an ine¢ c ie ntly high frequen cy of bankruptcy. Crucially, Bolton and Oe hmke (2010) ass ume that the CDS se llers obse rve the exact p os ition of the b uyer-cred itor, who th ere fore n ever gain s f rom dealing in CDS as s uch. By contrast, th e p res ent pap e r b uilds on the assu mption th at derivative (CDS) sellers know neithe r how m any se curities (b ond s) the he dge f un d h old s, nor h ow many d erivatives (C DS contracts) th e he dge fu nd en ds up h old in g. Th e latter ass ump tion app e ars ju sti ed b e cause de rivative s (CDS) are available from multip le s elle rs who do n ot know how many contracts have b een sold by the others, and to whom. 2The ide a that a he dge fu nd can us e its emp ty voting p owe r to create unc ertainty ab out the se curity payo/ an d p ro t on a n et long or a ne t sh ort p osition is als o pres ent in Brav and M atthe ws (f orth coming). In their mo de l, h oweve r, the on ly trade d asse ts are sh are s, an d the only way to create a s hort p osition is by sh ortin g th e sh ares . To retain voting p ower wh ile b e in g s hort the s hare s, i.e ., to bu ild an empt y votin g p os ition, the hed ge fu nd acquires n ake d vote s f rom other s hare holders th rough th e s hare lend in g marke t. Brav and Matthews ass ume th at th e h edge fu nd can d o so f or f re e u p to a ce rtain amount, and not at all b e yon d th at amount.This ass umption do es not work ou tside the sh are 2C f . C h r i s t o /e r s e n e t a l . ( 2 0 0 7 ) , w h o d o c u m e n t t h a t t h e a v e r a g e v o t e d o e sindeedsellforapriceofzerointhesharelendingmarket. 3 lend ing marke t, howe ver, b ec ause the h edge fu nd will have to pay f or votes b un dled with a c as h- ow into a s ecu rity. M oreove r, trad in g in de rivative s p res ents add itional pro t opp ortun ities for the hed ge f und . The tre atm ent of d erivatives an d empty voting in th is p ap er is entirely the ore tic al. Comm entators ge nerally agree that n o p re sently available d ata either proves or disp roves that th e issu es c on side red here are a seriou s problem, and that su ch data would b e d i¢ cult to come by (Hu and Black 2008a, 2008b ; M en gle 2009, p . 9; Brav an d M atthe ws, forth coming, msc r. p. 34). Hu and Black (2006, 2007, 2008a, 2008b ) p re sent at least anec dotal eviden ce , h oweve r, of th e problem o c currin g in ind ividu al in stan ce s. Given the explosive growth of de rivative s marke ts over the las t dec ade or so, it is als o p ossib le that the prob le m was n ot serious in th e past bu t may b ecome so in th e fu tu re . If this were so, the normative recomme ndations of th is p ap er cou ld b e s een as forestallin g a p otential problem from turning into a real one . The res t of this pap e r is stru ctured as f ollows. Sec tion I se ts u p the mo del. Se ction I I e xp lains the e qu ilibriu m c on cep t. S ection I I I solve s f or the equilib riu m. S ection IV prese nts c omparative statics. Sec tion V d is cus ses contractual remed ie s th at parties to d erivative c ontrac ts might adopt to solve th e p rob lem ide nti e d in this pap er; it als o addres ses exis tin g le gal limits. S ection VI con clude s. 1 Mo del Setup This sec tion intro duc es th e se tu p of th e mo de l: the two typ e s of traded asse ts (sec urities and de rivative s), th e three typ es of market p articipants (he dge f un d, liquid ity traders, and marke t makers), an d trading includ ing inf ormation. It con clude s with s ome remarks on th is se tu p. The basic s etup an d the equilib rium c once pt disc uss ed in th e ne xt se ction is similar to Kyle and Vila (1991), who m o d el the tradin g of a raide r who has the p ower to de clare a value- in cre asing takeover. In c ontras t to Kyle and Vila (1991), howe ver, th e present mo de l cons iders th e p arallel trad in g of two corre lated asse ts , in wh ich th e acquisition of a s u¢ cient amount of one of the m is require d f or th e p ower to de clare th e "takeover" in the rst p lac e. 1.1 Traded assets The re are two traded3ass ets with p erfec tly ne gatively correlated payo/s : sec urities, which will th rou ghout b e d enoted by th e letter X , an d d erivatives, which will throughou t b e den ote d by the le tte r Y . If th e sec urity pays v , th e de rivative p ays 1 v . Cons equently, th e derivative can b e interpreted as an in surance claim on the s ecu rity. In particu lar, if th e se curity we re a b on d, the d erivative 3" Tr a d i n g " d o e s n o t n e e d t o b e u n d e r s t o o d l i t e r a l l y i n t h i s m o d e l . I n p a r t i c u l a r , i t i s p o s s i b l e t h a t t h e d e r i va t i v e i s a c o n t r a c t t h a t i s s o l d o v e r t h e c ounter.Whatmattersisthattherebeanactivemarketforthecontractin w h i ch va r i o u s p a r t i e s c a n a c t a s s e l l e r s o r b u y e r s , w h i ch i s t r u e f o r m a n y d e r i va t i v e m a r k e t s . 4 cou ld b e a cre dit def ault s wap; if th e se curity we re a sh are , th e derivative cou ld b e a total equity return s wap. The s ecu rity payo/ v de p en ds on a binary ch oic e b etwee n two actions, which is d etermined by a vote of the sec urity h old ers. For e xamp le , if the se curity is a b ond , the choice cou ld b e whe th er or not to agree to a p rop os ed restructu ring; if th e sec urity is a s hare, it c ould b e whethe r or not to agree to a m erge r. Normalize th e p ayo/ whe n the "right" dec is ion is taken to v = 1 , and when the "wron g" dec is ion is taken to v = 0 . Each s ecu rity provid es on e vote; d erivative s d o not p rovide any vote s. Natu rally, a ration al, in formed, and un hedged se curity holder wou ld always vote for th e "right" de cision in orde r to rec eive v = 1 . As will b e d iscu sse d in the ne xt s ubs ection and the conclu ding remarks on the mo d el setup , this is ind eed what all s ecu rity holders are assu med to d o. The one e xc eption is the hed ge f und if an d b e cause the hed ge f und own s more de rivative s than sec urities , i.e., if the he dge fu nd is over-he dged an d thus h as an "e mpty" voting p os ition. Th e he dge fu nd s ability to b lo ck the "right" d ecision de p end s on wh ethe r th e hed ge f und s se curity-h old in g is ab ove some voting thresh old . Th e votin g thresh old is ass umed to b e a ran dom variable u niformly d is tributed on the unit interval. Th e ran domn ess c aptures un exp ec te d variation in voter p articipation , u nce rtainty arisin g f rom legal c on cerns , di/e re nt formal thresh old s for di/erent typ es of de cisions, etc. The votin g thresh old is as sum ed to b e inde p en dent of other exogenou s variab le s in th e mo de l, and it will b e in dep e nd ent of any trad ing activity sinc e it will b e only re veale d af ter all trad in g o ccu rs . The numb er of sec urities is normalize d to one (of which in n ites im al divis ion s are trad ed). S hort-s ellin g is allowed f or b oth de rivative s and se curitie s. 1.2 Market Participants The re are thre e typ es of risk-ne utral marke t participants: liquidity traders, on e he dge fun d, and comp etitive market makers. 1.2.1 Li qui di ty traders The liqu idity trad ers d o n ot act strategically. The y exogenou sly trad e qu antities ~x and ~y of s ecu ritie s and derivatives, resp ectively, where p os itive numb e rs ind ic ate that the liquid ity trade rs are sellin g, and ne gative numb e rs ind icate that the y are buying. The se trade s are n ot s ens itive to p rice , an d the sou rce of thes e trad es is n ot mo d elled. To motivate th ese trad es and th eir pric e in se nsitivity, one may th in k of large ins titutional inve stors and the ir regulatory con straints . For example, ce rtain p en sion fu nds might b e forced to sell b onds f ollowing a cred it d owngrad e of the b orrower. Similarly, n ancial in stitu tions might b e forced to purch ase cred it def ault swaps on certain b on ds the y hold. Or one may th ink of mutual fun ds h avin g to liqu idate part of the ir p ortfolio to mee t re demp tion re qu ests . Liqu id ity trade rs su pply of d erivatives, ~y , is s to chastic (ke eping in mind that the "sup ply" can b e n egative). W ith probability , the su pp ly is h igh ( ~y = y 5 state h ), wh ile with probability (1 ), s up ply is low ( ~y = y state l ). De n e the di/e ren ce b etween the se sup ply re alizations as y y > 0. For simplic ity, liquid ity trad ers su pply of sec urities, ~x, is ass ume d to b e cons tant. 1.2.2 Hedge f und The he dge f un d d o e s act s trategically. In itially, th e he dge f un d d o e s n ot h old 4any s ecu ritie s or de rivative s. It pu rchase s quantities x and y of sec urities an d de rivative s, resp e ctive ly, taking into account th e e/e ct of its trad es on the price (as explain ed b elow), its own votin g p ower, and its own votin g in centive s. As explained in the p re vious sub sec tion , holding x 0 se curities give s the h ed ge f und the voting p ower to imp lement the "wrong" d ecision with prob ability x (assu ming th at it is not p os sible to own more th an all of the ou tstandin g s ecu rities). Of c ou rs e, th e he dge f un d will on ly have an inc entive to us e this p ower if y > x. The he dge fun d in curs a nan cing cos tc 2 x2+ y2 .1.2.3 Mar ket maker s The m arket make rs ab sorb any e xc ess s upp ly or de mand ( ^x; ^y ) = ( ~x x; ~y y ).Sin ce th ey are risk-ne utral an d in p e rf ect comp e tition with one another, th ey pu rchas e or sell th ese quantities at p rice s that e qu al exp ec te d value, as explained in more d etail b e low. Market makers h ave rational exp ec tations, i.e. th ey obs erve the net s up ply of se curitie s ( ^x; ^y ) ; and up d ate the ir b e lief s ab ou t ~y . 1.3 Trading and Information Trad in g pro c eed s as follows. 1. Liquidity trade rs exoge nous ly s upp ly ( ~x; ~y ), whe re ~y is s to chastic as d esc rib ed in th e p revious sub sec tion. 2. The hedge fund observes ( ~x; ~y ) b ef ore s ub mitting its own market orde r (x; y ). 3. The marke t makers obse rve only net marke t s upp ly ( ^x; ^y ) = ( ~x x; ~y y ).Base d on th is ob servation , the y up date th eir b e lief s ab out th e exp ected value of the s ecu rities an d de rivative s, as explained in more de tail b elow. At the se value s (p rices ), th ey ll all n et orders ( ^x; ^y ). The as sum ption th at only th e hed ge fu nd obs erves liquidity traders ord ers is c ru cial, bu t it n eed not b e interpreted literally. A m ore lib eral and realistic interpretation is th at b oth th e hed ge f un d an d the market makers obs erve n et marke t su pply, but s in ce only the hed ge f un d knows its ow n orders, on ly th e he dge f und is ab le to back out liquidity trad ers orde rs. In a fu ller, d yn amic mo del, the he dge f und could grad ually adju st its trades to the availab le sup ply. 4O t h e r w i s e , t h e h e d g e f u n d s p r o b a b i l i ty o f w i n n i n g t h e v o t e w o u l d b e mi n f x; 1 g . I n p r i n c i p l e , i t i s c o n c e i va b l e t o a l l o w x > 1 i f s h o r t - s e l l i n g i n c r e a s e s t h e a m o u n t o f " s e c u r i t i e s " a va i l a b l e i n t h e m a r k e t . To s i m p l i f y m a t t e r s ,itisnotallowedinthispaper. 6 1.4 Remarks on the mo del setup The mo d el assu mes th at the hed ge f und is able to ac qu ire any amou nt x of se curities that it des ires . In partic ular, this ab ility do es n ot dep end on th e amount ~x su pp lied by liqu id ity trade rs. In re ality, it may of te n b e di¢ cu lt or imp oss ib le to acquire large blo cks of shares or b onds . Th ere are , howe ver, many situation s in which e xogen ous sales of se curities ~x are large , an d th e re ader m ay restric t th e applicability of th e mo del to such s itu ations . For e xamp le , many institution al investors sell all th eir h old in gs of a b ond if th e b ond s credit rating drops b e low a ce rtain th re shold. Moreover, in the mo del, an upp er b oun d on the amount x of secu rities th at th e h edge fun d c an acquire wou ld not change the h edge f und s s trategy, and th e only ch ange from th e re sults prese nted b elow wou ld b e that th e h ed ge f und might have to s ettle for the u pp e r b ound rather than its pref erred , higher p osition (i.e ., on e wou ld obs erve corner solutions). Relatedly, the assu mption that large p urch as es h ave no p rice imp act b eyond the probability u p date by the market m ake rs is not literally true . To go b ack to the ac qu is ition of se curitie s, it would p re sumab ly b ec ome harder and h arde r to n d add itional sec urities as the hed ge fu nd s p os ition grows , an d this would b e re e cted in higher trad ing c osts f or larger p os itions. M ath ematic ally, h oweve r, the ass ump tion of a n ancin g cost for the h edge f und h as th e s ame a/ect as ass uming inc reas in g trading c os ts for larger blo cks, so that nothing s ub stantive se ems to h in ge on th e as sum ption of con stant pric es con ditional on th e u p dated probab ility. Fin ally, it is a s trong as su mption that on ly th e on e hed ge f un d is ready to bu y large s take s, an d to c onside r ove r- hed gin g its se curities p osition and to vote the s ecu rities f or the "wrong" dec is ion . This e xclu des , rst, that any of the other market particip ants in the mo del, name ly in divid ual market m ake rs and liquid ity trade rs, who mu st hold th e re main in g s up ply of se cu ritie s, would ever hold more derivatives th an sec urities, or if they did, th at the y n everth eles s voted f or th e "right" de cision . On e ju sti cation f or this cou ld b e in stitu tion al, namely that re pu tational conce rn s or she er ap athy prevent market makers an d liquidity trad ers to vote for the "wrong" d ecision, or to overhed ge th eir sec urities p osition in th e rst p lac e. Se cond , the ab ove as sump tions rule out s trategic comp e tition with a s econd large player. For examp le, one can imagine a sec ond hed ge f un d trying to s hare the s p oils, or to b uy u p en ough of the s ecu rity at a low p rice to prevent th e rst he dge f und from e ver winn ing a vote for th e "wron g" d ecision. One way to j ustify th is res triction is to as sume ge nu in ely private in form ation on b eh alf of th e he dge fu nd , in p articular ab out liquidity trad er s trades . From a prac tic al p oint of view, ad ding anoth er strategic p laye r would c omplic ate the mo d el bu t not eliminate the u nd erlying ec on omic problem. For e xamp le , even if the sec urity we re trad ing at de ep dis count b e caus e of he dge fu nd s p re sen ce, an oth er large player c ould not ne ces sarily pro tably interven e by b uyin g up the entire su pply of s ecu rities if an d b e caus e that sec ond large player in cu rs s imilar nan cing cos t as the rst hed ge fu nd. More over, even if the s econ d large player cou ld pro tably do th is, then in exp ectation th e price of th e sec urity would re- ad ju st 7 to 1, so that the strate gy wou ld e nd up b eing n ot pro tab le afte r all. 2 Equilibrium Concept The ab ove as sum ption s on in divid ual b ehavior allow su mmarizing the s trategic interaction in two s im ple equilib riu m cond itions (Kyle 1984; Kyle and Vila 1991). First, th e ass umption that liqu id ity trad ers trade s are exogenou s mean s that liquid ity trad ers d ecisions ne ed n ot b e consid ere d at all. Se cond , th e assu mption that market-makers act as comp etitive price takers and ab sorb or su pply any deman ded qu antities ( ^x; ^y ) mean s that th eir b eh avior can b e sum marized by the pric e f unc tion. More s p eci c ally, p rices are entirely pin ned down by marke t- make rs rational exp ec tations of th e s ecu rity and de rivative p ayo/s. M oreove r, the re is e /ec tively on ly one pric e fu nction b e cause the payo/s of de rivative s an d sec urities are p e rf ectly ne gatively correlated. Let Px( ^x; ^y ) b e th e pric e of se curitie s and P 2y( ^x; ^y ) b e th e pric e of de rivative s. Fu rthe rmore, let ( ^x; ^y ) : R! [0; 1] de scrib e th e c orrectly in fe rred probability that th e s ecu rity will pay z ero con ditional on obs erved net sup ply of se curities and derivatives , ( ^x; ^y ). Th en market-makers equilibrium b e havior is fu lly cap tu re d by the following cond ition: i ( ^x; ^y ) = 1 i i ( ^x; ^y ) = ( ^x; ^y ) and Py =1P ( ^x; ^y ) i i; yi ( ; ) , x( ^x; ^y ) : Fin ally, obs erve that at th e voting stage , th e h ed ge f ned down by its h old in gs of sec urities an d derivatives . If th e hed ge fu n ritie s th an derivatives (x > y ), it will vote f or th e "right" d ecision; othe the "wrong" dec is ion (with mixin g p os sible only if x = y ). Conse qu e only has two true ch oic e variab le s, name ly its trad es x and y . Le t un d s pro t in s tate i 2 f h; l g , and (x) the he dge f un d s (p oss ib ly m os e s tates . Then the hed ge f un d s e qu ilibriu m strate gy is capture on dition : ; yi) maximize ( ; yi Pro t maximization : for eve ry i 2 f h; l g , (x s x j ^x; ^y . 8 ) . In cho osing its pro t-maximizing p osition s (x; y ), th e he dge f und will of cou rse take into acc ou nt the e/e ct of its trad es on pric es, i.e ., on th e prob ability inf ere nce of the m arket makers, ( ^x; ^y ). In th at s ens e, th e e¢ c ie nt marke t con dition imp lie s an inverse d emand cu rve agains t which the h ed ge fu nd s pro t maximization op e rates. Cons truc tin g an equilib rium p rinc ip ally require s th e de nition of s om e in fe re nce fu nction ( ; ) for which b oth c on dition s can hold simu ltane ously. In principle , ( ; ) equals th e probability that the he dge f und is able to implement the "wrong" votin g de cision, provid ed that it wou ld want to d o so in the rst place . That is , in p rinc ip le , ( ^x; ^y ) = E max f 0; min fx; E¢ cient markets : for some Px 1gg 1f y >xgNote , however, th at ( ^x; ^y ) is ob jec tively d e ned on ly at p oints ( ^x; ^y ) that are actually obse rved in equilibriu m. At other p oints, ( ^x; ^y ) is derive d from s ubje ctive o/-e qu ilibriu m b e lief s of marke t- makers . 3 Equilibrium This p ap er f o c use s on a f ull p o oling equilibrium, th at is, an equ ilibrium in which the obs erve d n et market s upp ly ( ^x ; ^y ) is id entical in b oth s tates of the world (h and l ), i.e., the h edge f und f ully hide s b ehin d th e n ois e. W hen liqu id ity trad ers are large sellers of d erivative s (or equ ivalently, small b uyers), the hed ge f und acqu ires a large amou nt of derivatives , vote s for the "wron g" d ecision, an d, if s ucc ess fu l, gain s on its derivative p os ition. W hen liquid ity trad ers are sm all se llers of de rivative s (or e qu ivalently, large b uyers), the h ed ge fu nd acquire s fe w de rivative s or e ven s ells th em, vote s f or the "right" voting d ecision, and gains on its holdings of the sec urity. 5To nd the equilibrium, the p ap er rst conj ec tu re s that it exis ts , and then pro cee ds to ve rify all the e qu ilibriu m cond itions. S om e of the more tech nical con ditions are re le gate d to the app e nd ix, inc lu ding a d is cus sion of th e exogenous parameter s pace for wh ich the equilib rium exists. It c an b e s hown that the equilib riu m con sidered he re is u niqu e for su ¢ ciently low value s of c, i.e ., f or su ¢ ciently low nanc in g costs for the hed ge f und . 3.1 Direct implications of the p o oling conjecture Certain relationsh ips b etwe en exoge nous and en dogenou s variab le s f ollow d irectly f rom the conj ecture that obs ervab le net market sup ply ( ^x ; ^y ) is identic al in b oth states, and yet th e hed ge fu nd is able to a/ect the vote di/erently in the two states . First, the hed ge f und mu st always b uy the same am ou nt of se curities , x . Se cond , th e h edge f un d mu st bu y d i/ere ntial qu antities of de rivative s y< yhlthat p e rf ectly o/set th e d i/e re nce b etween y and y . That is, it mu st b e th at ^y = y yh= y yl, implyin g yh yl= y y = : 5I nthealternative,separatingequilibrium,thehedgefund sholding s a r e f u l l y r e v e a l e d , a n d h e n c e t h e h e d g e f u n d e a r n s z e r o p r o t . To " e n f o r c e " t h i s e q u i l i b r i u m , t h e r e m u s t b e a f u n c t i o n ( ; ) s u ch t h a t t h e h e dgefundcannotdeviatetoatradewithpositivepro tsineitherstate.L e t x = ~x ^x a n d y = y ^y . T h e n t o h o l d t h e h e d g e f u n d t o z e r o p r o t s , i t w o u l d h a v e t o b e t h e c a s e t h a t f o r a l l ( ^x; ^y ) , l 0 :C o m b i n i n g t h e s e tw o i n e q u a l i t i e s , o n e c a nobtainthecondition h =(y+ x)[x ( ^x; ^y )] c2 x 2 + (y + )2i 0 h= ( x y ) ( ^x; ^y ) c2 x2+ y2 2 x y 2 ( ^x; ^y + y2 + +x(x y ): ) c x2 y + 22 B u t t h e n f o r a n y ( ^x; ^y ) s u ch t h a t > x y> 2 + y2 + y + 2 i + x ( x y ) 2 ( ^x; ^y ) ch x2 a n d x; y > 0 , i t w o u l d f o l l o w t h a t f o r c s m a l l e n o u g h , <0; 2 x y 2 9 w h i ch i s i n c o n s i s t e n t w i t h t h e d e n i t i o n o f a p r o b a b i l i ty f u n c t i o n . T hird, to crea te di/er ent sec urity an d de rivati ve p ayo/ s in the two state s and he nce pro t op p ortu n ities f or the h ed ge f un d, it mu st b e th at the prob abilit y of th e "wro n g" d ecisi on b eing ado pted di/er sb etwe en the two state s. On e con ditio nf or th is is yl< x< yh, s o that th e h ed ge f un d will vote di/er ently in the two state s. Th e othe r con ditio n is th at x> 0 so that the hed ge fu nd can actu ally in u e nce the votin g ou tcom e. F in ally, s ince po olin g me an s that the m arke t mak e rs c an not te ll th e two state s ap art, it mus tbe th at ( ^x ; ^y ) = x 6.To ge ther with th e e¢ cie nt mar ke t cond ition, this imp lies Py( ^x ; ^y ) =1 Px( ^x ; ^y ) = ( ^x ; ^y ) = x . 3. 2 Fi rs tor d er c o n di ti o n s 7The p ro t maxi miza tion cond ition re qu ires that th e hed ge f un d cann ot do b etter in eith er state by ad jus tin g its trad es. Ass u ming th at th e pro t fu nc tion is di/e renti ab le, this re qu ires that th e rs torde r cond ition s for an opti mu m are satis e d. Th at th ep ro t fu nctio n is in dee dd i/ere ntiab le can be p rove d alon g the lin es of Kyle an d Vila (199 1). Gi ve n th e re su lts of th e p re vi ou s su b -s e cti on , ar ou nd th e eq uil ib riu m for st at es h an dl , th e p ro t fu nc tio n ca n b e wr itt e n (w h er e F (x) is th e pr ob ab ilit y th at th e h ed ge f un d ca n ge t th e "w ro n g" d ec isi on im pl e m en te d, gi ve n its se c uri ty ho ldi ng s x): h D en oti ng by su b sc rip ts i th e de riv ati ve of af un c tio n wi th re sp e ct to its ith ar gu m en t, th e rs tor de rc on dit io n s ar e: l 2 ( ^x; ^y ) y = (x y ) ( ^x; ^y ) c(x; y ) = x [1 F (x)] + y F (x) xP= (y P x) [x ( ^x; ^y )] c2 (x; y ) (=^x; ^y ) c + y x xPx( ^x; ^y ) y Py2 xx2 2 y +2 y2 x ( ^x; ^y ) c2 + y2 2x 2x + y2 ) = (yh x) 2 x) [1 + 1 ( ^x; ^y )] [x @ x (x h@ 7[ ) = (yh y (yh ) = (x l l ) = (x ( ^x ; )] cx ^y ( ^x yl) 1 ( ^x; ^y) + ( ^x; ^y ) cx = 0: yl) 2 ( ^x; ^y ) ( ^x; ^y l l ...] @ h = 0; @ ; ^y) + [x ( ^x; ^y )] cy= 0; @ @ x (xh= 0; @ @ y (y) cy R e c a l l t h a t w e h a v e a s s u m e d t h a t i t i s n o t p o s s i b l e t o6o w n m o r e t h a n alloftheoutstandingsecurities,i.e.,x 1. 10 3.3 Equilibrium values Comb in in g th e rst-order cond itions an d the d irec t implication s of the p o oling con jec ture yie ld s th e f ollowing equilibriu m value for x : x = max = x ( + c) [1 c] 2c; 1 ; 2 =x h ; ^y y 2c ; ( + c)y; y+ (1 c) ; ( ^x ) = c x The u pp er b ound on x come s f rom the assu mption that it is not p os sible to own more than all the outstand in g se curities , wh ose su pply is normalized to one . Assu ming that we are n ot at th e c orn er solution x= 1 , th e solutions for the oth er en dogenou s variab les c an b e written = ( + c) [1 3c] yh = ( + 3c) [1 c]2c ; ( ^xand the impac t of trade s on the p robab ility inf ere nce f un ction ( ; ) at the ; ^y ) = c + x equilib riu m p oint is ( ^x l l 1 ; ^y (1 )= ( c) [1 c] 2c ; ( + c) [1 c] 2 c: )=c x =c 2 3.4 Other conditions To ve rify that th e he dge f und s trade s are in dee d pro t maximizing, it remains to verif y th e s econd -order cond itions , an d that the hed ge fu nd s equilib rium p ro ts are p ositive in b oth s tates (since th e he dge f und always h as the op tion n ot to trad e). As alread y mention ed , it is also ne ces sary to verif y the as sump tion mad e ab ove th at x 2 (0; 1) and that no se curity h old in gs outside this inte rval yield s highe r pro ts. Fin ally, since the de rivation ab ove as sum ed di/erentiability of ( ; ), it must b e checked that the hed ge f und can not earn h igh er pro ts at p oints where ( ; ) is n ot d i/erentiable, i.e., whe re equals e ith er on e or ze ro. Verif ying the se con dition s is re le gated to th e app e ndix, whe re it is sh own that all cond itions hold su b je ct to certain restric tions on th e p arameter sp ace. 11 4 Comparative Statics The primary variable of inte res t is the prob ability that value- des troyin g de cisions will b e adop te d, that is x = max ( + c) [1 c] ; 2c 1 : At the internal s olu tion, this probability is in creasing in , the u ctuation in liqu idity trade rs d erivative trades , and de cre asing in c, the h edge fu nd s n ancin g cost. The p robab ility is in creasing in b ec ause greater u ctuation in liquidity trad es p rovides more camou age to th e hed ge fun d. Th is e nables the he dge fu nd to take greater n et p osition s, with c oncomitantly greater p ro ts con ditional on obtain ing the de sired votin g re sult. This in turn make s it more attractive f or th e h ed ge f und to ac qu ire a more p owerf ul voting p os ition. As the noise go es to ze ro, s o do es th e he dge f und s votin g p os ition an d he nce the probab ility of value- des troyin g de cisions. The prob ability is dec reas in g in c b ec ause greater nan cing costs make it more costly f or the hed ge fu nd to acquire large votin g b lo cks an d d erivative p osition s. Th is is p erhaps mos t clear in the expres sion s for the e qu ilibriu m holdings of de rivatives , wh ich are centered arou nd x bu t sh if ted downwards by an amou nt c. As sh own in th e app e ndix, the h ed ge fu nd d o e s not even make p os itive pro ts in b oth state s of the world if the trad ing cost parameter c is greater than 8equilib riu p 1=8 ; in th at case , fu ll p o oling is no lon ger a s m. ustainable 1 ( ^x ( ; ^x ^y 8 ; ^y 1 1 12 The slop e of th e in fe re nce an d h enc e of the pric e fu nction with resp e ct to th e obs erve d net sup ply of sec urities , , re ects the amb igu ou s nature of inc re asing the h edge f und s s ecu rity h old in gs. On th e one han d, greater s ecu rity h old in gs make it less attrac tive for th e he dge fu nd to vote f or th e "wron g" de cision. On the other h and, greater se curity holdings als o make it easier f or th e h edge f und to get th e "wrong" d ecis ion adopte d, if it wants to. Re ec tin g this du al ch aracter of inc re as in g th e h edge f un d s se curity p os ition, the inf erre d probability of the "wron g" d ec is ion b eing adop te d can eith er rise or f all if the hed ge fu nd in creases its sec urity holdings, d ep en ding on the relative s iz e of and c. If > c, ) > 0, i.e., whe n th e hed ge fun d bu ys more sec urities, the inf erred probab ility of a "wron g" vote go e s down . By c ontras t, if < c, ) < 0 , i.e ., th e infe rred p robab ility of a "wrong" vote go es up wh en the h edge f und bu ys more se curitie s. 5 Contractual Remedies [this s ection is p articularly inc om plete] E q u i l i b r i u m b e h a v i o r f o r c > p1 = 8 r e m a i n s t o b e v e r i e d . I t i s p r o b a b l y n otanequilibriumforthehedgefundnevertodoanytradesbecauseata ninitialtradeofzero,thehedgefund smarginalcostoftradingiszero . S o i t i s l i k e l y t h a t t h e r e w i l l a l w a y s b e s o m e p o s i t i v e p r o b a b i l i ty o f t h e hedgefundacquiringsomesecuritiestoattempttoimplementtheneg ativevotingoutcome. The discu ss ion thus f ar h as not cons id ered legal or contractual limitation s on the "empty voting" s trate gy pu rsu ed by th e hed ge f un d. This sec tion brie y outlin es two of th e main legal con straints b efore pu ttin g f orward a contractual solution, wh ich th e p articipants of th e d erivative market sh ou ld nd in the ir se lf -inte res t to adopt. 5.1 Legal limits On th e legal side , the he dge fu nd might n d its b ehavior incrimin ate d un der di/e re nt do ctrin es in the d ebt and e qu ity case . In the equity case, holding a su ¢ ciently large blo ck of voting s hare s would qualify the hed ge f un d as a controllin g sh are hold er. Controlling shareholde rs , h owever, arguab ly h ave a du ciary du ty n ot to exercise th eir votin g p ower agains t th e b en e t of th e corp oration in f urth eran ce of s om e private b e ne ts , here th e p ayo/ on th e d erivative s. In th e d ebt c as e, creditor votes in bankruptc y c an b e disallowed if they are not c as t in "go o d f aith ," an d cas tin g th e votes "e mpty" with the intention of lim iting recovery by cred itors would arguab ly qualif y as not b eing in "go o d f aith." In each case , h oweve r, app lication of th ese d o c trines requires that the e mptine ss of the h ed ge f un d s voting p osition b e kn own by fe llow sh areh old ers, cred itors, or the ju dge, as th e case may b e . At p res ent, this is n ot ne ces sarily guarante ed by e xisting disc los ure obligation s (Hu and Black ...). Moreover, limits on "e mpty votin g" do n ot ap p ear to apply to creditors outside of bankru ptcy. 5.2 Contractual p osition limits and information p o oling Participants in the derivative market have the p ossibility and the in centive ,h oweve r, to adopt a contractual solution to the "empty voting" problem. In the mo d el, the hed ge f und s gains trans late dire ctly into loss es for liquid ity trad ers in th e d erivative market. Wh en liquidity trade rs bu y many d erivative s, the he dge fu nd bu ys fe w, votes the "right" way, and the reby d ecrease s the payo/ of the derivatives . W he n liqu id ity trad ers s ell m any de rivatives , the he dge fu nd b uys many, votes the "wrong" way, and the re by in cre ases the p ayo/ of the derivatives . Liqu idity trade rs sh ould th erefore p re fe r and comp e titive marke t m ake rs would b e forc ed to provid e de rivative contracts that exclude the p ossib ility of "emp ty voting." At prese nt, c ertain de rivative contracts, in p artic ular CDS, alread y c ontain claus es that purp ort to forc e the c ontrac t own er to exerc ise any voting rights in the corres p ond in g se curity with a vie w to maximizin g the valu e of that se cu rity. As Hen ry Hu an d Be rn ie B lack n ote , however, the se c laus es are hardly e nf orce able b e caus e th e required in formation is not gen erally availab le (Hu an d Black 2008a, p. 733; 2008b , p p. 682-3). It would app e ar di¢ cu lt and cu mb ersome to collect votin g inf ormation on a frequ ent basis. A more eas ily impleme ntable p rotec tive mechanism would b e to limit th e amount of h edging th at u sers of derivatives are allowed to do, i.e., to in sert p osition limits into derivatives contracts. This would re nde r th e "empty voting" 13 strate gy relative ly u nattractive to h edge fu nd s who nee d to b e able to overhe dge a s iz eable p os ition of voting s ecu ritie s to make the strategy pro table. To b e s ure , p osition limits could b e circumvente d by b uying d erivatives from mu ltiple se llers. S elle rs cou ld rese rve the contractu al right, however, to p o ol inf ormation at th e pay-out stage to en sure that p os ition limits were res p ec te d. The in formation c ou ld b e p o oled in th e hand s of a third party s ub je ct to s trict con de ntiality p rovisions. The third party would colle ct p ay- ou t inf ormation f rom all d erivative c ounte rp arties and only re lease any in form ation if it f ound that ind ividual recip ie nts had e xc eed ed th eir p osition limits. 6 Conclusion Commentators have b e en worryin g ab ou t the votin g inc entives of a sec urity holde r wh o is "ove r-h ed ge d," i.e., wh o holds more o/-s ettin g d erivatives th an votin g se cu ritie s. Th is p ap er p rovides th e rs t rigorous de monstration that bu ild in g su ch an "empty voting p os ition" c an b e a p ro tab le strate gy for a he dge fu nd if sec urities and de rivative s trade in p arallel noisy m arkets. Th e strate gy will b e all th e more pro table, an d valu e-d estroyin g votes all th e more like ly, as trading c os ts de crease an d market liquidity in creases , as has ge nerally b e en the trend in d erivatives marke ts over the last de cade. This p ap er the re fore add s reason to take the "e mpty votin g" prob lem s erious ly. At the s ame tim e, the mo d el sh ows that the h edge fu nd s gains come at the exp ens e of liqu id ity trad ers in the derivative markets, with los ses to s ecu rity holders merely arisin g as collateral d am age . Henc e liquidity trad ers in th e de rivative markets have th e right in centive s to pu sh for a contractual solution of th e "emp ty voting problem" dis cus sed in this pap er. In p articu lar, they may insis t on us in g contracts with p osition limits. 14 A p p e n d i x A d d it i o n a l E q u ili b r i u m C o n d it i o n s T h i s a p p e n d i x v e ri co n si de re d in th e m ai n te e s r e m a i n i n g c o n d it i o n s f o r t h e f u ll p o o li n g e q u ili b ri u m xt. 7x Th e d eri va tio n of th e he d ge fu nd s pr ot m ax im izi ng tra de s as su m ed th at th e he dg e fu nd s pr ob ab ilit y of wi nn in g th e vo te ar 2 (0; 1) ou nd th e eq uil ib riu m p oi nt eq ua ls x, an d th at th e de riv ati ve of th e pr ob ab ilit yf un cti on is 1. Th at is , th e de riv ati on of op ti m al tra de s on ly co ns id er ed x 2 (0; 1). It n ee d s to b e ve ri ed , rst , th at th e op ti m u m tra de ac tu all yf all s int o thi s int e rv al, an d, s ec on d, th at no x ou tsi de thi s int er va l yi el ds hi gh er p ro ts . Fo r x = ( + c) [1 1) h (x; y ) jx 0 c]2 c 2 (0; wou ld not b e pro table. 8 Positive pro ts 15 0 : S o 2x + y2 to h old tru e requires th e followin g re strictions on th e exoge nous parameters: ( + c) [1 c] > 0() 1 > c: ( + c) [1 c] < 2c() 2c( + c) [1 c] : < h Next, che ck that n o x0outside (0; 1) wou ld yie ld h igh er pro ts for the he dge = (x y ) ( ^x; ^y ) c2 f=und , given ( ^x; ^y ). First, do es n ot de p en d on F (x), s o the global 0 c2 2x+ y2 maximization of llhas the same cond itions as the re stricte d optimization ab ove, with the s am e outcome. S econ d, h(x0) < h(x ) for any x0 1 sinc e we f ou nd that x 2 (0; 1) maximize s heve n u nd er the assu mption th at F (x) = x throughou t, while in reality F (x) = 1 for all x0 1 , an d is increasing in F (x). Third , f or x 0, F (x) = 0 , s o marke t makers know that v = 1 f or s ure, i.e ., ( ~x x; ) = 0 , and he nce t h e h e d g e f u n d w o u l d b e e a r n i n g n o n p o s it i v e p r o t s , a n d t h i s d e v i a ti o Th e he dg ef un d al w ay s h as th e op tio n no t to tra de an d e ar n ze ro pr ot s. Th us f ull p o oli ng ca n on ly b e an eq uil ibr iu m if th e n h ed ge f un d m ak es p os iti ve p ro ts in b ot h s tat e s. U s in g th e eq uil ibr iu m va lu es de riv e d in th e m ai n te xt, w e m u st ha ve h (x ; yh) = (yh ] c2 2 x ) [x x x + y2 h 2 : 2 2 ( + c) c) 2 ( + c) [1 c] 2c4 c 0() 2 ( + c) [1 c] 2c ( + c) We als o mus t ) = (x c2 ) x yl x + y2 l 2 have l(x ; yl 2 [1 ( + c)]: The p ositive pro ts cond ition c an thu s b e 2 stated 2 max 2n ( + c)2; 13 c2; [1 ( + c)] o 2 + 2( + c) [1 ( + c)] c() c 2 "0; 13 r1 8# ^ 2 2 13 = 2 2 2(1 2 The up p er b ou nd for 1 c + 23 2( + +1 c) 3 c = 1 p 1 6c2 implies c + 13 > c; 3 p 1 6c 2 ( + c) [1 c] 2 c4c [1 c] 2 c 0() 2 ( + c) 2 2 (0; 1). i.e ., it contain s the con dition 1 9 Second-order conditions To ens ure that we are at an opti mu m, we nee d to ch eck the sec on d d eriva tive s. To f acilit ate th is , we res trict th e sear ch to lin ear f unc tions (; ), > c requ ired f or x 2 [1 c] p1 6c with slop es 1 and 2; ^y a s give n in the previ ous sub se ction . As p ointe d ou t in the main te xt, (; ) is ob j ectiv ely de n ed only at the p oint ( ^x), so th ere are p ote ntiall y man y di/er ent f unc tions (; ) that c an s ustai n th e equil ib rium . The re fore, to th e exte nt that the s econ d -ord er cond ition sf or lin ear (; ) con sider ed h ere yie ld restr ic tions on the para m eter s, it is p oss ible th at th ese restr ic tions wou ld not ap ply if a broa der c lass of fun ction s were c on side red . U n d e r t h e l i n e a r i t y a s s u m p t i o n , t h e s 16 e c o n d d e r i v a t i v e s a r e : 1 @2 h @ x2 1= 2 2 =22 2h 2 @ y2 2h 2l @ x2 2l @ y2 2l c @ c @ @ y @ x = 1 + 1 @ = 2 c @ = 2 2 1 c @ @ y @ x = 1 2 The con ditions for an op timum are thus9 2 c < 0 (2 c) (2 2 c) ( 11 22)> 0 Using the resu lts f rom the rs t- orde r con dition s, the rs t of the se con dition s c = 2 c +2= x require s 2c +c 2 1 < 0 ) c (1 2 c) < [1 ]) 2 12 1 2 9T hecondition 2 2 2 1 4c + 1 p8 c c<0isimpliedby 2 1c<0:Thecondition 2 2c<0isimpliedbythe rstconditionand c ) (2 2 c ) ( 1 2)2 ( 2 1 )2 1 17 (1 [1 ) ]c c > 0 : F i n a l l y, t h e c o n d i t i o n ( 2 2 c)(22 c) ( 1 2 >0isimpliedbytheprecedingcondition. Fo x x (1 ) 2= 2 ( + c) [1 c] + c [2 (1 ) 3 c] (1 )= 3 22 5c 6 c + 4 0) c 2 [0; r1 6) ^ 2 23 c 21 3p 1 6c2;which is gu caranteed by 2 th p os itive p ro t c ondition . As c an b e checked algeb raically, th 2 r) pro t con dition als o implie s th e up p er b ound f or from th e( rst cond ition, bu2t n ot the lower b oun x . 2=7 1 T h e Corner solutions [NEED TO CHECK] 10 The rst-orde r ap proach assu med that ( ; ) is d i/erentiable in b o s ) nts. e This, however, can only b e true on a limited interval of ( ^x; ^y ) s e ( ; ) 2 [0; 1].... + c o 3 11 n Summary of parameter restrictions In s um, we have the f ollowing parameter re strictions f rom the re qu d nt that x 2 (0; 1) and that pro tsc b e p os itive in b oth states: c o n d i t i o n r e q u i r e s c 1 < 2 c( + c) [1 c] : 3 p 21 6c; 13 c + 1 p 1 6c2 3 c 2 " 0 ; 2 2 3 r 1 8 # ra lin e ar f un c tio n an d c > 2= 7, th e se c on dor d er c on dit io n s al so re qu ire > 12 Ref er ence s 1. Bolt on, Patri ck, and M artin Oeh mke . 201 0. Cred it Def 1 p2 8c2 4c + 1: 18 ault Swa ps and th e Emp ty C red itor Prob lem. Wor kin g pap er, Colu mb ia Un ive rsity. 2. 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