From 1971 to 1995 he was a professor at the Free University of Brussels and at the University of Antwerp. In 1995, Delbaen became a full professor at the ETH Zurich, remaining there until his retirement in 2008. He is still a professor emeritus at ETH and, since 2011, also a guest lecturer at the University of Zurich.[1]
Together with Walter Schachermayer, he proved a general form of the fundamental theorem of asset pricing for (locally) bounded semimartingales, replacing the condition of "no arbitrage" with the term no free lunch with vanishing risk (NFLVR).[8] The two also proved a version for unbounded price processes.[9]
In a joint paper with P. Artzner, J. M. Eber and D. Heath, he introduced the concept of (coherent) risk measure on a finite probability space.[10] Delbaen later generalized the concept to general probability spaces.[11]
Delbaen, Freddy; Schachermayer, Walter (1994). "A General Version of the Fundamental Theorem of Asset Pricing". Mathematische Annalen. 300 (1): 463–520. doi:10.1007/BF01450498.
Delbaen, Freddy; Schachermayer, Walter (1995). "The existence of absolutely continuous local martingale measures". The Annals of Applied Probability. Institute of Mathematical Statistics: 926–945.
Delbaen, Freddy; Schachermayer, Walter (1999). "The fundamental theorem of asset pricing for unbounded stochastic processes". Mathematische Annalen. 20 (2). doi:10.1016/S0167-6687(97)80683-X.
^"Freddy Delbaen". ae-info.org. Academia Europaea. Retrieved January 28, 2023.
^Delbaen, Freddy; Schachermayer, Walter (1994). "A General Version of the Fundamental Theorem of Asset Pricing". Mathematische Annalen. 300 (1): 463–520. doi:10.1007/BF01450498.
^Delbaen, Freddy; Schachermayer, Walter (1999). "The fundamental theorem of asset pricing for unbounded stochastic processes". Mathematische Annalen. 20 (2). doi:10.1016/S0167-6687(97)80683-X.