Professor Los was economist and senior economist of the Federal Reserve Bank of New York (1981–87), senior economist of Nomura Research Institute (America) (1987–90), and chief US economist of ING Bank (1991–93). His private financial risk consultancy, EMEPS Associates, was incorporated in Wilmington, DE, USA, in 1986.

He was associate professor of banking and finance at the Nanyang Technological University in Singapore (1995–99) and associate professor of finance at Adelaide and Deakin universities in Australia (2000–2001) and Kent State University in Ohio (2001–5). In Singapore and Ohio, he contributed to the creation, design and organization of new MSc programs in financial engineering combined with newly built academic financial trading floors. In 2005–6, he taught economics and finance courses at the Kazakh-British-Technical University in Alma Ata, Kazakhstan, in two new joint BA programs of the London School of Economics. In 2007–8, he was a visiting professor of financial management at the Peter F. Drucker and Masatoshi Ito School of Management of the Claremont Graduate University in Southern California. He supervised Master and PhD theses at these universities.

Professor Los is a life fellow of the American College of Forensic Examiners; fellow of the Australasian Institute of Banking and Finance; senior member of IEEE; and member of the American Economic Association, the American Finance Association, the Financial Management Association International, the Global Association of Risk Professionals, the International Association of Financial Engineers, the Econometric Society, and the New York Academy of Sciences.

Professor Los uses advanced signal processing techniques to measure, analyze and value the non-stationarity risks of global financial markets, weather systems (e.g., for agribusinesses), and large-scale strategic investment projects (e.g., for oil and gas exploration, mining, bio-engineering and pharmaceutical companies). He actively presents and discusses research papers at meetings of international academic associations. For banking and insurance companies he does risk analysis and distinguishes between insurable, probability-measurable, Keynesian risk and uninsurable, residual, Knightian epistemic uncertainty. In 1998, he won a best paper award from The Asia-Pacific Risk and Insurance Association in Singapore for his exact performance attribution analysis of the origins and consequences of the 1997 Asian Financial Crisis and for simultaneously providing an exact solution for optimal cash overlays for global portfolio management.

One of his best experiences as an undergraduate business student was as an AIESEC (Association des Étudiants en Science Économiques et Commerciales) intern in a family-owned coal transportation business in Antwerp, Belgium, in 1973, where he had to take an active role and assume responsibility for an efficiency-enhancing reorganization, apply business theory to the process, build a network of contacts, and start to organize his own personal worldview.

He blogs occasionally about the history of accounting and finance and their enduring impact on economic and financial development, the current threat of government intervention to the liberty of the financial markets, and the meaning and importance of the 2nd Amendment of the US constitution for the defense of individual liberty.

Professor Los is listed in Marquis’ Who’s Who in the World, Who’s Who in America, Who's Who in Asia, Who is Who in Finance and Business, Who's Who in Science and Engineering, Who’s Who in American Education, and its various other editions. He is on the Dictionary of International Biography Honours List for his “outstanding contribution to financial economics.”