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Shorting in Speculative Markets
Author(s) -
NUTZ MARCEL,
SCHEINKMAN JOSÉ A.
Publication year - 2020
Publication title -
the journal of finance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 18.151
H-Index - 299
eISSN - 1540-6261
pISSN - 0022-1082
DOI - 10.1111/jofi.12871
Subject(s) - economics , economic bubble , marginal cost , value (mathematics) , monetary economics , carry (investment) , constant (computer programming) , microeconomics , financial economics , econometrics , finance , mathematics , computer science , programming language , statistics
In models of trading with heterogeneous beliefs following Harrison‐Kreps, short selling is prohibited and agents face constant marginal costs‐of‐carry. The resale option guarantees that prices exceed buy‐and‐hold prices and the difference is identified as a bubble. We propose a model where risk‐neutral agents face asymmetric increasing marginal costs on long and short positions. Here, agents also value an option to delay, and a Hamilton‐Jacobi‐Bellman equation quantifies the influence of costs on prices. An unexpected decrease in shorting costs may deflate a bubble, linking financial innovations that facilitated shorting of mortgage‐backed securities to the collapse of prices.