The article substantiates the portfolio block as a key tool for diversifying a transport company's business in the context of high demand turbulence, accelerated digitalization, and stricter regulatory requirements. It demonstrates that a systematically organized set of activities, services, customer segments, and infrastructure and digital assets allows for building a multi-loop growth model, reducing dependence on the cyclicality of individual markets, and increasing business resilience to external shocks. The theoretical framework is based on classical concepts of corporate strategy and modern approaches to managing uncertainty, such as synergy, real options, and managed variability. The paper proposes a logic for the strategic and economic design of a portfolio block, combining an assessment of industry attractiveness and competitive position. It is shown that a properly designed portfolio block increases operational efficiency, profitability, and predictability of cash flows, while simultaneously ensuring compliance with ESG and regulatory requirements.