The hyperscalers’ race to build AI capacity is reducing the share of revenue left as free cash flow – the cash generated by their operations after capital spending. Margins have declined across all four firms; Microsoft retains the strongest position, while Alphabet’s has narrowed sharply and Amazon’s has turned negative. These funding pressures came into focus last week, when Alphabet shares fell about 13% and Amazon dropped around 7% in after-hours trading following their results. Strong AI demand was overshadowed by concerns over cash generation and further spending, alongside disappointing sales or forecasts.The difficulty is that data centres must be financed well before their eventual returns are known. Lower free cash flow margins therefore need not mean that these investments will disappoint, but they leave less scope for shareholder payouts and may increase reliance on cash reserves or borrowing. The key question is whether operating cash generation can catch up with capital spending. A sustained recovery in margins would ease funding concerns; further declines accompanied by rising debt would increase pressure on companies to demonstrate that their investment plans can deliver adequate returns.