Research Review | 5 June 2026 | Risk Management

Measuring Bubbles via Put-Call Disparity: A Model-Free Approach
Robert A. Jarrow (Cornell U.) and Simon Kwok (U. of Sydney)
May 2026
This paper introduces simple, model-free lower and upper bounds for measuring the size of asset price bubbles. Assuming only that the market satisfies no-free-lunch-with-vanishing-risk and that all trading strategies are admissible, our framework avoids restrictive parametric models and the no-dominance assumption. We demonstrate that put-call disparity provides an observable lower bound, and is economically justified by short-sale constraints. Additionally, the lowest price of an out-of-the-money (OTM) call option determines the upper bound. To ensure empirical reliability, we modify these bounds using data-driven regularization and bootstrap methods to disentangle genuine bubble signals from market microstructure noise and to reduce reliance on thinly traded deep OTM options. Using S&P 500 index option prices from 1996 to 2025, we document a sustained bubble during the COVID-19 era and capture market exuberance preceding the 2000 dot-com and 2008 financial crashes. In addition, the empirical study suggests that the market violates no-dominance and is incomplete.

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Off the Grid, Italy Edition…

The Capital Spectator is taking an extended Memorial Day holiday and trading NJ for Italy for the week ahead. Postings will be light to (probably) non-existent during the interim. The US-based routine resumes again on June 2. Ciao!

Book Bits: 23 May 2026

Yuppies: The Bankers, Lawyers, Joggers, and Gourmands Who Conquered New York
Dylan Gottlieb
Review via The Wall Street Journal
“Violent gentrification” is an eye-catching phrase akin to “Canadian depravity” or “Luxembourgish aggression.” If it exists, it isn’t obvious. In “Yuppies: The Bankers, Lawyers, Joggers, and Gourmands Who Conquered New York,” Dylan Gottlieb does his best to alarm readers about his subject and their nefarious doings, such as moving into dicey neighborhoods and turning them into havens for fragrant bakeries and adorable cafes.
The term “yuppie” is as closely tied to the 1980s as “hippie” is to the ’60s. Young urban professionals have usually been discussed in comic terms, by such writers as Tom Wolfe and P.J. O’Rourke, with gentle mockery or even wry affection. Mr. Gottlieb, a professor of history at Bentley University, produces nearly 300 pages on the topic without a trace of humor, except in quotation.

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Headline Inflation Surges, but Core Measures Keep the Fed on Hold

Inflation has climbed in the wake of the energy shock stemming from the Middle East, and economists expect the upward pressure to persist in the months ahead. The Federal Reserve is monitoring the data closely, but it left interest rates unchanged at its most recent policy meeting late last month. The Fed funds futures market is still assigning high odds to the Fed holding steady at the next several meetings. The question now is how high inflation will rise before the central bank feels compelled to resume rate hikes.

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