“…In reality, the credit rate is always higher than the deposit rate. Such a market constraint brings new difficulties in the problems of hedging, investing and shortfall risk minimization (see Bergman [4], Kane and Melnikov [13], Korn [15], Bart [3], and also Cvitanić and Karatzas [8], Cvitanić [6,7], Föllmer and Kramkov [11], Karatzas and Shreve [14], Cvitanić, Pham and Touzi [9], Soner and Touzi [21] regarding other market constraints).…”