Investment behaviour of economic agents in conditions of uncertainty and shocks

Purpose. To justify a theoretical and methodological approach to studying the investment behaviour of economic agents under conditions of uncertainty and shocks; to develop a dynamic mathematical model of the investment behaviour index that combines the rational and behavioural components of investment decisions, as well as to conduct its numerical validation using data on the Ukrainian in 2019–2026. Methodology. The comparative analysis method was applied to systematise conceptual approaches to investment behaviour under conditions of uncertainty (real options theory, economic policy uncertainty indices, behavioural finance); the method of statistical generalisation was applied to process secondary data from the World Bank, the OECD, the European Business Association, and the Ministry of Economy of Ukraine for 2019–2026; mathematical modelling methods (differential equations, logistic functions, integral calculus) were used to construct a dynamic model and conduct its numerical validation. Findings. It has been established that the investment behaviour of economic agents under shock conditions is shaped at the intersection of rational (expected return, cost of capital) and behavioural (fear of loss, herd behaviour, excessive caution) components, whilst uncertainty raises the threshold for investment decisions in accordance with the logic of real options theory. An investment behaviour index B(t) has been constructed as a weighted aggregation of five sub-indices (expected return, uncertainty, access to finance, institutional trust, subjective risk of loss) and a dynamic model of its response to a shock and subsequent recovery. Numerical testing using data from Ukraine revealed a sharp fall in the index in 2022 (from 0.52 to 0.21), followed by a recovery to 0.51 in 2026, which is consistent with published data on the gradual recovery of companies’ willingness to invest despite the war. Originality. The rational and behavioural components of investment decisions have been combined within a single dynamic model, which integrates real options theory with an equation describing the response to a shock and subsequent recovery, tested on secondary empirical data from Ukraine’s wartime economy. Practical value. The results can be used by government bodies responsible for investment policy, international partners and financial institutions to assess the effectiveness of investment incentive tools, forecast the trajectory of recovery in investment activity and justify the sequencing of reforms to the investment climate.