Nassim Nicholas Taleb (born ) (Arabic: نسيم نيقولا نجيب طالب ) (alternative spellings of first name: Nessim or Nissim) is a literary essayist, epistemologist, polymath, researcher, and former practitioner of mathematical finance. [2][3][4][5] A specialist in financial derivatives [3] (while critical of the industry), he held a "day job" in a lengthy senior trading and.