De Groot has held positions at executive level in various industry sectors at companies listed at the stock exchange. Prof. dr. Bert de Groot has several supervisory board positions. He advises boards and executives. He is executive professor of the programs The New CFO's and The New CIO's - CTO's- CDO's. He scientifically proved the existence of the Golden Ratio in the economy.Prior to his executive board and CFO position at Randstad Holding N.V. (staffing services), he was part of the Management Gist Brocades N.V (now DSM), the biotech and pharmaceutical company, Finance director at Unisys Inc, the information management company. He advised KPN, telecom multinational and did cooperate recovery at Pharming N.V. (life sciences). Advised at Boer & Croon Executive Management. As CFO he delisted AM N.V. (project development and housing). He was Rector Magnificus of Nyenrode Business Universiteit. CEO, COO and CFRO of Erasmus Universiteit Rotterdam Holding B.V. and member of the MT of the Erasmus School of Economics. General Manager of Maritime Economics & Logistics. He held two Chairs : Business and Economic Cycles and Governance and Strategic Investments.In his 2021, 2022 publications, he found the Golden Section to be the relationship between economic and business cycles. Technological Forecasting & Social Change (TF&SC) ranks 11 out 400 Business Journals. It brings new light on economic multi cycle behavior. Listen to the Canadian Podcast: https://anchor.fm/techinsights/episodes/New-discovery-of-the-golden-ratio-in-the-economy-e17cbsa .He makes forecasts for 25 OECD countries and forecasts for companies. He started and co-produced the Randstad Holding forecasting on econometric basis. He gave new insights in competition for the Hamburg-Le Havre ports and the port of Rotterdam. He is often quoted in TF&SC and was quoted in the Harvard Journal. He forecasts the world stock markets. Bert de Groot studied econometrics at the Erasmus Universiteit Rotterdam (EUR) and has followed management programs at IMD (previously IMI), Nyenrode, Wharton, INSEAD and Harvard. De Groot was awarded his PhD by the ESE for his thesis ‘Essays on Economic Cycles’ and an Economic Indicator for the Economy based upon staffing services, people working at Randstad. EICIE was published in ESB.